Phase II:
How Hot Does it Run and How Many Continuous Rounds Can We Fire?

It has been almost a year and a half since the original tests, and a review of the data we collected from those outings created a few additional questions that needed to be answered. We noticed that the running temperatures of the P-416 were consistently lower than those taken during the same circumstances with a direct gas impingement system. It makes perfect sense that the absence of the gas tube redirecting hot gasses into the action would relate to lower operating temperatures but we wanted to find out exactly how much of a difference it would actually make, especially during abnormally heavy usage. This allowed us to set up and began phase II.

Phase II would be another type of endurance test where large amounts of ammo would be fired, in very long, continuous and uninterrupted bursts, possibly bringing the test rifles to the point of catastrophic failure. Upon reaching the predetermined number of rounds, the temperature of the rifle would be measured in several areas, and the testing would immediately continue, allowing for the residual operating temperatures to continue to increase. No cooling time would be allowed.

Since BETA C-Mags are readily available and have worked well for us in past testing of this type, we decided to use them as the baseline and go with 100- round continuous mag dumps. We determined that the complete test would consist of 1,000 rounds, barring any type of system failure. After continuously firing each 100-round burst, the surface temperature would be measured on the following parts: the bolt face, the chamber area, the gas block and the muzzle brake. The surface temperature of the barrel would be measured occasionally but was not considered a vital measurement for purposes of these tests. The temperatures would be measured in the Fahrenheit scale with a Geneva Scientific Model TLL950LS Infrared thermometer. This thermometer has a working temperature range from -32° up to +950° and no contact is necessary to slow down the testing or require cumbersome embedded sensors.

Since we determined that it was going to be possible to reach a catastrophic failure point, for safety purposes, each test rifle was fitted with a KNS precision tripod adapter allowing it to be fired from a standard MG42 anti-aircraft tripod, and both series of tests also employed a set of KNS Precision Spade grips. This combination would allow the shooter to place his body well behind the action of the firearm and not require a cheek weld on the stock only inches from the chamber.

We decided to use Wolf 62-grain, FMJ .223 for several reasons. First, there was an abundance on hand, and if both test rifles reached their maximum number of rounds allotted for the testing, we would need at least 2,000 rounds. Secondly, and most importantly, this was to be one hell of an endurance test and it is almost universally agreed that steel-cased ammunition has the potential to be tougher on chambers than traditional, brass-cased ammo. Contrary to sometimes popular internet and urban legend, we have run tens of thousands of rounds of this ammo during testing firearms of all calibers, types and styles over the years with no adverse effects whatsoever.

Load Up

All available BETA C-Mags were loaded and the remainder of the ammo was loaded onto steel stripper clips for use with a speed loader. We didn’t know really what to expect, but having heard stories about “fire till failure” drills with other rifles, we dressed properly including correct sight and hearing protection. The 16-inch barreled P-416 was mounted on the MG42 anti-aircraft tripod and the baseline temperatures were taken. (It should also be noted that the rifle had been test fired and several magazines were fired in measuring the rate of fire before this round of testing began. Given the high endurance of the original test model we decided not to bother cleaning the rifle before starting this round of testing. Since it was obviously dirty, a quick burst of Rem-Oil was applied through the dust cover prior to beginning this test.) The air temperature was a seasonal 41° above zero with no measurable wind and all parts to be checked were very close to our established “room temperature” this day. (A complete set of charts with all round counts and recorded temperatures are included with this article). After establishing that everything was at a base temperature, it was time for the testing to start.

Drum number 1 was loaded and emptied in a single, sub 10-second burst. This was the kind of shooting that we were always warned against because it was potentially destructive and usually pointless in situations where “placing multiple hits on approaching targets was necessary.” It is also precisely the kind of shooting that many serious class III recreational shooters (who have no current approaching enemy targets at the time) really enjoy. The rifle was quickly cleared and temperature measurements were taken in the chamber area, the bolt face, the gas block and the muzzle brake. All were recorded and the next drum was loaded in approximately 90 seconds time.

The bolt was closed on drum number 2 and it was emptied as flawlessly as the first. Measurements were repeated, the next drum was loaded. As the P-416 effortlessly continued to chug along through drums 3, 4, 5, 6, 7 and 8, we wondered if it would indeed make the 1,000-round count we set without a major stoppage.

Drum 9 ran as smooth as the first and it wasn’t until approximately 1/3 into the 10th and final drum that the rhythmic sounds we were getting quite used to screeched to a halt. A quick survey of the situation showed nothing more than a severely cracked magazine feed tower had allowed it to spread and log jam several rounds up inside the action. The loose rounds were quickly cleared and an 11th full magazine was immediately inserted, giving way to another 100-round stream of steel casings, that never ended until the magazine was empty. The final readings were taken and the Phase II portion of the P-416 test was officially over. We didn’t have any reason to believe it would not make it through the whole 1,000 rounds in this harsh manor, but we were still relieved and impressed that it did. A count of the rounds fired through the malfunctioning magazine gave us a total of 1,036 rounds fired throughout the test.

Phase II, Part II

All the data gathered during the P-416 portion was quickly filed, and a second rifle was brought out to duplicate the testing with, and to take direct comparative measurements from, while in exactly the same conditions. This second rifle was a standard direct gas impingement system with an M4 contoured 16-inch barrel, and utilized the same lower receiver and mount setup for continuity.

After taking baseline temperatures the shooting began in the same manor as the first rifle. The first BETA C-Mag was inserted and the first 100-round magazine dump was completed as easily as with the first rifle. It was getting a little darker at this point and the glowing gas tube was highly visible under the rail system. We quickly swooped in with the instrumentation, gathered the necessary numbers and we were onto the second burst.

Drum number 2 was inserted, the bolt was dropped and the range filled again with the same rhythmic beat that had been played since we were set up and started the testing. The gas tube started glowing almost simultaneously with the beginning of the firing, evidenced by the residualheat in it, the barrel and the gas block. The cyclic rate remained smooth and even, and all 100 rounds found their mark in the impact area. The numbers were gathered and drum number 3 was inserted.

As soon as the impact area was in the sights the trigger was engaged and drum 3 was on its way to being rapidly emptied. The gas tube again glowed immediately, and this time the cyclic rate was almost instantly erratic. About 30 rounds into the third drum the cyclic rate started slowing and eventually sputtered to a stop. Pulling the charging handle rearward, anempty chamber was discovered. There had been a gas tube failure and there was not enough pressure to bring the bolt carrier back far enough to pick up a new round and chamber it. Another round was cycled by hand and fired only to have the same result. The magazine was pulled, the gun cleared, and the measurements recorded. Test over. Total rounds fired in rifle number 2 was 264.

Heat Transfer

As discovered through the measurements we recorded, heat was indeed transferred into the action of the firearm through the gas tube at a much faster rate than with the piston gun. The numbers that seemed to indicate the most significant difference were the temperatures of the bolt itself. The bolt face temperature was measured after every magazine was emptied and it reached a higher temperature after firing only 200 rounds with the direct gas impingement gun than it did even after firing over 1,000 rounds through the piston gun. Another factor that plays into the equation is friction, which is greatly reduced in the P-416 by the removal of the gas rings and the silicone nickel coating, which creates an extremely smooth surface. The maximum temperature the bolt face reached in the P-416 was 122° and that was recorded immediately after firing 1036 rounds. The maximum temperature the bolt face reached in the direct gas impingement rifle was 133° but that was only after 264 rounds, the failure point for this system.

Chamber temperatures recorded with the direct gas impingement rifle reached a maximum of 115° and was recorded after 264 rounds, the maximum number of rounds fired. The P-416 reached a similar temperature of 119° after firing 600 rounds. The maximum chamber tempera ture measured in the P-416 was 131° immediately after concluding the testing at 1036 rounds. All temperatures were measured in the rear of the chamber through the barrel extension.

The gas block of the P-416 retained much more heat after firing than the gas block of the direct gas impingement rifle. While the maximum temperature recorded with the direct gas impingement rifle was after only 200 rounds, it only reached a temperature of 339°. After firing 200 rounds in the P-416, the gas block reached a temperature of 498° and spiked at 697° after firing 800 rounds. Gas block temperatures fluctuated greatly throughout the testing but seemed to dissipate much faster in the direct gas impingement rifle. The mass of the gas block is much greater in the P-416 and the free flowing transfer of heat ends there in that particular system as opposed to allowing the flow rearward through means of the gas tube.

Much of the barrel temperature increase is due to the friction of the projectile being forced down the bore. Since the focus of our testing was to check for changes directly related to the differences between the direct gas impingement system and the gas piston systems we did not bother collecting significant data in this area.

Conclusion

We did not really know what to expect when we started this test. The number of rounds fired in the short time allowed was way beyond the normal use of any standard black rifle. The rifle system itself was simply not designed to fire that many rounds without failure. We have all seen enough melted gas tubes and have a good enough understanding of how the system works to know this kind of abuse is well past its intended use. The point of the test was to fire as many rounds as the rifle would withstand, and record the data to that point. Since the P-416 was still functioning at the end of the testing, we still do not know what that end point really is. Maybe a “fire till failure” test is something we should explore in the future. All this writer knows for certain is that the POF-USA P-416 rifle system was designed without the limitations of a standard black rifle and continues to perform in ways quite unrealistic to the original design. There seems to be plenty of active debate about the piston operating system versus the direct gas impingement design and there may never be a “perfect” system for everyone. Just like there are desired barrel lengths, calibers and mounting platforms that some see as mission critical and others see as simple options, the operating system may just be another choice for the end user to determine and remain the topic of another endless debate in the gun world. While there may be valid reasons to stick with a time proven direct gas impingement system in some instances, it is clearly becoming obvious to some that the newly designed piston systems on the market today also have definite advantages. It was not very long ago that the implication of a rifle that could double as a PDW and a SAW would be considered unrealistic at best. Today, thanks to POF-USA, that might not seem quite so far fetched.

Use Your Ears

If you shoot a lot of fully automatic firearms, especially to extremes such as this, your ear can become an important tool. A smooth and even cyclic rate is usually a sign of things working well. When the cyclic rate varies up and down (when shooting the same ammo) or is erratic in any way, it is often a sign of something wrong. A gas leak is an easy one to diagnose as the cyclic rate often slows drastically from start to finish during a long burst. It can be anything from a failing gas tube to a loose gas key but is usually a sign of a gas pressure problem.

During the testing of a new rifle a few years ago, it was decided to do a full BETA C-Mag dump during a lull in the shooting at a well attended private shoot. Since it was a very short barrel (11.5 inches) and had a brake that was quite loud, after 35 or 40 continuous rounds it caught the attention of several participants. The cyclic rate started out in the area of 950 rounds per minute and was slowing at an even pace. By the time the rifle finished the magazine, it was running no faster than 450 rpm. Several people came right over and commented that it sounded like the gun was “running out of gas” and sounded like an outboard boat engine as the tank ran dry. After clearing and cooling, the gun was examined and an improperly staked (and very loose) gas key was found to be the culprit. As usual, your senses, in this case your hearing, can give you more information than you know how to process if you only listen to it.

Sources

P-416 Rifle System
POF-USA
Dept. SAR
23623 N. 67th Ave.
Glendale, AZ 85310
Phone: (623) 561-9572
Fax: (623) 321-1680
E-mail: sales@pof-usa.com
www.pof-usa.com

BETA C-Mags
The BETA Company
Dept: SAR
2137B Flintstone Drive
Tucker, GA 30084
Phone: (770) 270-0773
Fax: (770) 270-0599
E-mail: cmag@betaco.com
www.betaco.com

Spade Grips & Tripod Adapter
KNS Precision, Inc.
Dept: SAR
112 Marschall Creek Road
Fredricksburg, TX 78624
Phone: (830) 997-0000
Fax: (830) 997-1443
E-mail: sales@knsprecisioninc.com
www.knsprecisioninc.com

Wolf Performance Ammunition
Sporting Supplies
Dept: SAR
1125 North Lance Lane
Anaheim, CA 92086
Phone: (888) 757-WOLF
Fax: (714) 632-9232
www.wolfammo.com

Every war is different. Every battleground has diverse characteristics. Each mission, whether a military role or civilian law enforcement detail varies greatly in its specific purposes. It seems almost impossible on the surface that a single weapon system could adapt and function in such a range of climates and missions, but the familiar M16 is still going strong. From a lightweight carbine to a heavy barreled LMG, the M16 weapon system has been fulfilling the role of America’s primary service weapon for more than 40 years and it doesn’t seem it will be replaced wholesale anytime soon.

The earliest history of the inception and design of the black rifle bas been chronicled numerous times and it is not the intent of this author to rehash this historical material other than a very brief and condensed historical summary. There are many credible sources for this information including The Complete AR-15/M16 Sourcebook by Duncan Long, The Black Rifle I by Blake Stevens, Black Rifle II by Christopher R. Bartocci and an extensive Colt M16 ID Guide in the Machine Gun Dealers Bible by Dan Shea. This article will focus on the versatility of the M16, the characteristics that have allowed the metamorphosis from the original designs to the current battle rifle of the 21st century and possibly beyond.

Although there are a countless number of model designations for these rifles from numerous manufacturers, for simplicity purposes in this article, the designation “M16” can be assumed to be a fully automatic rifle while the designation “AR-15” makes reference to the semiautomatic version.

A Very Brief History

While its initial roots are clearly in the Stoner designs of the early 1950s, like most designs, the multiple lug bolt head, lockup into a barrel extension, and gas system principle can be traced back farther. It was at ArmaLite where this all came together. The first heavy public exposure to the black rifle started in the wet and humid environment of the tropics with the earliest variations sent to US troops in Viet Nam. There were many positive responses at first, but after the ammunition/propellant change, the black rifles were plagued with an extremely lackluster initial impression and poor performance in the field. Problems were eventually minimized after several rounds of intense testing combined with numerous committee change recommendations. Many alterations in production were initiated including chamber dimensions, rifling twist ratios, firing-pin changes, redesigning the flash hider and charging handle, and (against the advice of many people) the addition of a forward assist assembly. Along with ammo and gunpowder refinement, proper maintenance, and problems addressed with early magazines, the early version of black rifle as we know it today was on its way to becoming the cornerstone of the modern American military arsenal.

As early as 1963, Colt started manufacturing this “new” rifle in semiautomatic only with the civilian population and the law enforcement community in mind. Sold as the AR-15 Sporter it was virtually identical to the M16 with the exception of the fire control group. With an early retail price of $189.50 it was marketed to the hunting and sporting community as a beacon of a new wave of manufacturing technology allowing it to be lightweight while remaining accurate and effective. Although several minor changes have been made to separate the function of the semiautomatic version of these rifles from their fully automatic relatives over the years, and to keep them from being easily converted to fully automatic, they remain wildly popular and an enormous civilian market thrives today. Numerous upgrades and model enhancements of the civilian line of semiautomatic variants have followed very closely to those designed for the fully automatic models keeping them on a fairly level playing field.

With the 1977 expiration of Gene Stoner’s patent on the M16 gas system, several companies sprang up and started manufacturing their own versions of this popular rifle. The trademark model name of “AR-15” was, and still is, owned by Colt, and they are still one of many businesses that manufacture this weapon system and its many configurations.

Modularity is King

At the heart of the black rifle is the versatile lower receiver. This portion of the firearm is the section considered by federal law to be “the firearm” by definition. The lower receiver is the portion of the firearm that contains the trigger group and the pistol grip as well as the magazine well. Also attached to the lower receiver is the buffer tube and stock. This is the part that requires purchase through a licensed federal firearms licensee (if ordered from an out-of-state dealer) and the paperwork that goes along with any other firearm purchase, depending upon the laws of the State of the buyer. Every other part of this firearm may be ordered directly by the end user and requires no federal licensing or paperwork. All other parts, including the upper receivers and the barrels are treated just like any other non-regulated parts.

The upper receiver plays an equally important role in the mechanism. The upper receiver is the point of attachment for the barrel and the housing for the bolt, bolt carrier and charging handle. It is attached to the lower receiver by two takedown pins that are operable without the aid of any tools. The upper and lower receivers may be separated and rejoined at any time without fear of losing any components under normal handling. This may be attractive for size considerations when breaking down for transportation or when changing the characteristics of the rifle for a specific task.

Several rifle configurations may be assembled on a single lower receiver simply by swapping out barreled upper receivers. Specific tasks may require features unique to that task but may not be desirable to others. This is where the real beauty of the black rifle comes in. Unlike most other firearms, the characteristics of the black rifle can be altered at any time, and reversed back again, just by changing upper receivers. It is indeed more than a weapon; it is truly a “weapon system” as it is often properly referred as.

For obvious reasons, an entry-type rifle may consist of a very short barrel and either iron sights or a zero-magnification dot-type sight. A varmint hunting rifle may be much more effective with a long barrel and high power telescopic sight. With a black rifle, both of these configurations are only a quick upper receiver swap away with no lack of performance in either field.

There are barrels ranging from the 7-inch* “Kitty Kat” barrel from DPMS (www.dpmsinc.com) to a 24-inch Varminter Extra Heavy Barrel from Bushmaster Firearms (www.bushmaster.com) and a multitude of lengths in between. (* Under Federal Law a rifle barrel has to be over 16 inches in length to be a legal Title I firearm. By purchasing or registering the rifle as a Short Barreled Rifle, the owner can use any barrel length at will. With registered machine guns, the barrel length is not a legal stipulation under Federal Law and any length barrel may be used). There are not many rifles that allow the flexibility of swapping out barrel lengths without the necessity of tools in less than 30 seconds like this system. Additionally, another major advantage is the sights are part of the upper receiver as well, so there is no need to re-zero after making this swap. If multiple barreled upper receivers are owned, they can all be sighted-in and swapped as desired with a complete return to zero with careful handling and the correct ammunition.

From Plinking to Protecting

If there is any one thing that can always be counted on in the firearms community, it is American Ingenuity and the desire to make something bigger and better. (Sometimes smaller and better, in this case.) Fortunately, this has proven to work well in transforming the once light .223 Rem. (5.56x45mm) rifle into something left only to one’s imagination and budget. With the ease of changing upper receivers, the transformation from the original caliber to a completely new round is almost as simple. Since the upper receiver holds the barrel, bolt and bolt carrier, this is the portion of the rifle where the caliber of the ammunition to be utilized is determined. Thanks to many able minded firearm enthusiasts, these rifles can be converted to almost any caliber ranging from .17 to .50 BMG with minimal (if any) temporary modifications to the lower receiver. From the luxury of plinking for recreation on a budget or additional training, to having the stopping power to assist our front line fighters in the War on Terror, the black rifle can be custom configured to suit every application.

One of the most popular subcaliber units among black rifle shooters is the “Atchisson” .22LR conversion manufactured by Jonathan Arthur Ciener, Inc. (www.22lrconversions.com). When utilized with the recommended ammunition, properly maintained and operated, they provide hours of plinking fun in semiautomatic AR-15s or full automatic fun when used in conjunction with a registered M16. On the opposite end of the ammunition spectrum is the .50BMG Upper Receiver from Watson’s Weapons Inc. (www.watsonsweapons.com). This upper receiver actually allows the use of the massive .50 BMG round when attached to your lower receiver. It functions as a single-shot rifle that must be partially taken down to be reloaded between shots.

One of the most popular pistol caliber conversions would include the 9x19mm (Luger) conversion. First introduced in 1985, Colt offered a 9mm blowback-operated submachine gun that worked quite well. Most of the characteristics were the same as the standard rifle, making operation simple for anyone who had utilized or trained on the 5.56x45mm rifle. A special magazine (both 20-round and 32-round) was developed for the much shorter 9x19mm round and a block was pinned inside the standard lower receiver’s magazine well to accommodate the smaller magazine while utilizing the same magazine release. A civilian version was soon to follow in semiautomatic only with a 16-inch barrel. Other than the upper receiver and bolt differences, only the buffer was changed to a heavier one, and a few of the trigger group parts were slightly modified. In the 1990s, the US Drug Enforcement Agency adopted a silenced version of this rifle. The Department of Energy also adopted a very short variation known as the Model 633, commonly called a “DoE Upper.” The 633 had a 7-inch barrel, collapsible stock and a front handguard to keep the operators hands from straying in front of the muzzle.

Several other companies started manufacturing these pistol caliber conversions with numerous types of feeding systems. While a few emulated the Colt style mag-well block and use the factory Colt 9mm magazines, others used highly modified magazines reworked to fit the interior portion of the factory magazine well. Although many of the modified magazines work very well, they are often expensive and the availability is less than desirable in most cases. Even though there are several manufacturers of aftermarket (any non-Colt) black rifles including several Caliber conversions, the pistol caliber most often encountered remains the 9x19mm.

Many different calibers in black rifle variations have been written about here in the pages of Small Arms Review over the last 10 years. While there are new caliber combinations coming out at an amazing rate, some of the latest ones we are familiar with include the Alexander Arms .50 Beowulf and 6.5 Grendel, (www.alexanderarms.com), .502 Thunder Sabre by Cloud Mountain Armory (www.bigborecanyon.net) and lastly the .45 Bushmaster (www.bushmaster.com). We will be testing the .45 Bushmaster for a future issue of Small Arms Review very soon. Some of the more common calibers include, but are not limited to: .308 NATO*, 7.62x39mm and 6.8SPC and can be found from multiple vendors. (*.308 NATO (7.62×51) requires a different lower receiver due to the longer interior dimension of the magazine well necessary to accommodate that particular round).

Feed Me, Seymour!

Like the hungry man-eating plant named Seymour in the 1960s cult classic film Little Shop of Horrors, a black rifle is always hungry and never seems to be fed enough. Firearms, especially those in a military role, are no exception. The earliest magazine design of the AR-15 was a 25-round magazine, which had problems due to being straight, and was immediately replaced with a 20-round magazine. The first ones were steel “waffle” pattern magazines, which were also immediately replaced with the standard aluminum 20-round magazine that eventually evolved into the 20-rounder so common today. In the mid 1960s, a 30-round magazine was manufactured with a slight curve and it seemed to work great in all new rifles but had a hard time feeding in some, including the earlier ones. This was corrected in part by keeping the top portion of the magazine straight like the 20-round version and starting the curvature at the bottom of the magazine well. These magazines still had a reputation for jamming if they were loaded to 30 rounds, and the SOP was load to 28 rounds. This was corrected later by stabilizing the follower with equal leg lengths.

In order to address this “need for feed,” Colt experimented with a belt-feed mechanism that operated with a modified upper and lower. With a 20-inch barrel this unit weighed in at almost 8 1/2 pounds without the bipod or ammo box. The belt fed M16 never made it to production.

Fast forward to the early 1980s and bring Jonathan Arthur Ciener back into the picture. A manufacturer primarily specializing in sound suppressors at the time, Jonathan took it upon himself to redesign and reintroduce the concept of a belt-fed AR-15 and M16 and made them available to the general public. When they were evaluated for the now defunct Machine Gun News in 1992, this writer had the pleasure of working on the article and spending some trigger time with these guns. We were provided with both a semiautomatic model and a fully automatic model. They were built on factory Colt AR-15 and M16 rifles, and like Colts early design the upper and lower receivers were both modified. The Ciener system had a few very interesting points. First, the belt-feed mechanism could be removed from the weapon and it would again accept factory magazines. Second, Ciener produced some of the belt boxes which locked into the magazine well, as in the original design.

We tested them under several conditions with many types of ammunition in semiautomatic and full automatic. We tested it in belt-feed and magazine feed. We tested it with and without the addition of a sound suppressor. In summary it performed excellently. The only drawback was that in the case of a jam it was a “4-handed” operation to clear it and have it up and running quickly, but with a little practice it could be done quite efficiently. It also used a proprietary, modified link that was quite expensive at the time compared to standard unmodified links. These were sold for a few years but were eventually discontinued due to the enormous amount of time necessary to manufacture them.

There are a few current belt-feed systems for the black rifle but nothing yet has reached a mass marketing level. In the March 2003 issue of Small Arms Review (Vol. 6, No. 6), the Shrike 5.56 from Ares Defense (www.aresdefense.com) was covered in great detail as it was due to be released en masse around the time of publication. To this date, it is still being manufactured, released and shipped in very small quantities due to several redesign upgrades and improvements. The great attraction to the Shrike 5.56 is the fact that it works in conjunction with a completely unmodified lower receiver. All attempts at a belt-fed black rifle in the past have required major lower receiver modifications. Like the Ciener, model it can be fired from belt or box magazine but in the case of the Shrike 5.56, when the belt is out, a box magazine is simply inserted, the rifle charged and firing is uninterrupted. There are no parts to take out or change over. We are anxiously awaiting mass shipments of the Shrike 5.56 and will certainly test the newest production model as soon as they are shipped.

Another interesting belt feed option for the black rifle is the XMG from BRP Guns (www.brpguns.com). The XMG34 is essentially an MG34 “upper receiver” designed for use on an M16 lower receiver. Currently in its 5th year of production this inexpensive alternative to an original MG34 has been receiving great reviews for years. Available in 8mm and in .308, they are popping up at ranges nationwide and are becoming more popular with every passing year. They will function in fully automatic when used in conjunction with a registered lower receiver and require only a small (nonpermanent) modification to function.

Seeing a need for a belt-fed black rifle that is inexpensive to feed, the master of the miniatures, Lakeside Machine of Tippmann Arms fame decided to design a .22LR belt fed upper receiver with a similar mechanism to the popular Tippmann 1/2 scale miniature machine guns. (www.lakesideguns.com). This upper receiver, available for both semiautomatic and fully automatic function, was tested in the April 2006 (Vol. 9, No. 7) issue of Small Arms Review. The only modifications required to the lower receiver in this assembly are the exchange of the factory buffer and the suggested replacement of the hammer spring.

Understanding the demand for more ammo capacity than the 30-round magazines were able to provide, the Beta Company, of Atlanta, Georgia (www.betaco.com) worked with Jim Sullivan of the old ArmaLite and the M16 design fame, the original inventor of the 100-round C-Mag. Sullivan worked as a consultant with Beta Company in the early developmental stages of the new Beta C-Mag and with the introduction and advances in plastic materials and its ability to keep tight tolerances the C-MAG as we know it today has developed into an extremely reliable system, all while keeping weight to a minimum.

Mounting Madness

We live in a market driven economy and combined with the simple truth that necessity is the mother of invention, some “solutions” have been presented to us for “problems” we may never have known existed otherwise. In the last several years there have been an enormous number of accessories manufactured for mounting on MIL-STD-1913 rails. Along with these accessories came a mad rush for mounting platforms, and the standard factory handguards on the AR-15 and M16 are quickly being antiquated and replaced with new and improved rail systems. There are several to choose from including the Knight Rail Interface System (RIS) and Rail Adapter System (RAS) (www.knightarmco.com), VLTOR VIS System (www.vltor.com), POF-USA Predator Rail System (www.pof-usa.com), LMT Monolithic Rail Platform (www.lewismachine.net) and many more. All of the aforementioned have been of excellent quality.

For those not needing the precision, or wishing to spend the amount of money those mentioned may cost, some simple handguard replacements have been introduced that incorporate rails into them and some rail adaptors have been manufactured that simply bolt on to the existing A2-type handguards. A few of those have been utilized for testing devices like vertical grips where a slight amount of movement was not detrimental to the system and they performed fine. Other applications like mounting optics or more “load bearing” accessories would probably not be recommended for the latter systems.

All the new configurations and types of intended deployments these systems are capable of bring the necessity of new support equipment. One area where a serious advancement has been made is in the sighting systems available. Electronic “dot type” sights are very popular for close-up work and there are many types and styles. A few extremely popular systems include the EOTech Holographic Sight (www.eotechinc.com), the Aimpoint CompM4 (www.aimpoint.com) and the Trijicon ACOG (www.trijicon.com). While each system has distinct advantages the author is very familiar with the EOTech model 552. It has several settings for use with a night vision monocular as well as the standard day settings. The Holographic Sight is placed in a forward position on the top rail and utilized as usual during normal daylight. During low light the monocular is mounted behind it so the operator can use it at night without having to re-zero the weapon.

Along with the popularity of low or zero magnification electronic sights, the demand for a well-made, high quality, Back Up Iron Sight (BUIS) has been high for use during a potential electronic failure. Several contenders on the market include the Troy Industries, Inc. Folding Battle Sight (www.troyind.com), the GG&G Flip-Up Sights (www.gggaz.com), and A.R.M.S. Inc., #40 Folding Sights (www.armsmounts.com). An interesting front sight is the POF-USA FTA2005 Front Sight. It is not a folding sight but a stationary sight that is hooded for an extremely fast target acquisition and has been found to be complementary to use in conjunction with “dot-type” sights or as a stand alone with the correct rear BUIS. Due to the great number of new sight requirements, many of the modern rifles are available with a removable carry handle. Once the familiar carry handle and rear sight is removed, a standard MIL-STD-1913 rail is exposed to be used alone or in conjunction with these new sights and rail systems.

Another interesting new front sight was recently introduced for the black rifle. It is made by KNS Precision (www.knsprecisioninc.com) and is actually a circular “peep” with a crosshair in it. Initial testing appears it is fast and accurate and we are anxious to spend more time with this new front sight as well as several more of their latest offerings.

As a Catch-22, these new mounting platforms that were spawned from new items in need of mounts have spun off their own items made to be mounted on this newly available space. There are several devices available for mounting on MIL-STD-1913 rails including visible lasers, IR lasers, and lights. optics, night vision, camera equipment and many more items. Some earlier available items that were designed to mount on standard handguards or directly on the barrel have even been redesigned to mount directly on a rail system due to the high proliferation on later models. A prime example is the new rail mount 40mm LMT M203 Grenade Launcher. This tried and true M16 accessory used to mount on the barrel of the standard black rifle and a special handguard replaced the factory A1 or A2 handguard issued with the rifle. With the new rail mounted version, no additional handguards are necessary and due to the nature of the mounting system there is no longer any stress on the barrel as it is allowed to free-float with many current rail systems.

AR Accessories

As mentioned previously, several companies exist today just to service this weapon system. A quick glance around the Internet or any large, stocking gun shop will uncover thousands of items geared toward users of the AR-15 and M16 weapon systems. A look at KNS Precision and their product line will unveil several components for the black rifle useful in simple preservation roles such as pins that are designed not to rotate and egg-hole the aluminum receivers at the thin section supporting the hammer and trigger pins. They carry a variety of sights for target, plinking, competition and tactical applications and even manufacture a set of Spade Grips so you can shoot the rifle in the same manor as a 1919A4 with butterfly grips or an M60D model. We tested these grips in the May 2007 (Vol. 10, No. 8) issue of Small Arms Review and we found them a blast to shoot, especially with a pintle mount and Beta C-MAG. They are well made and functioned flawlessly.

While you are in research mode, take a peek at some of the products in the Command Arms Accessories line (www.commandarms.com). Some of these accessories manufactured for the AR-15 and M16 weapon system look more like they came back from a fact finding mission from the 22nd Century than from Ivyland, Pennsylvania where they are located. With accessories and upgrades from buttstock to muzzle, the only part of the original weapon system that looks familiar is the distinct shape of the receiver section. Watch for a piece in an upcoming issue of Small Arms Review where we take a “Plain Jane” AR-15 and give it the complete CAA treatment while testing it every step of the way. We are looking for something that really enhances performance and not just cosmetics and we have been assured we will not be disappointed.

Back to the Future

There is one unique feature of the black rifle that is as controversial as all other designs combined. This would be the way the gas system of the firearm operates and whether changing it is considered an upgrade or downgrade by the user. The black rifle operates with a direct impingement gas system in the following manner. When the rifle is fired, the rotating bolt is in its locked position in the barrel extension. As the bullet passes a gas port located under the front sight, some gas is bled off into a gas port and directed through a gas tube to the rear. The hot gas pressurizes the gas tube and the rear end of the pressurized tube is the gas key located on top of the bolt carrier with the gas thus exerting rearward pressure on this movable part. This pressure starts the bolt carrier traveling rearward, unlocking the bolt via its cam pin in the cam path on the carrier, and initiating the extraction. The bolt carrier travels rearward, and the projectile exits the bore evacuating the pressurized gas from the gas tube, ending any rearward pressure from the gas system. That time under pressure is critical to reliability and is dictated by the amount of time the bullet is traveling in front of the gas port. As the bolt carrier passes into the buffer tube (concealed in the stock) the fired casing is ejected. Met with a forward amount of spring tension from the now compressed buffer spring, the bolt carrier is returned to the front, picking up a new round from the magazine, loading it in the chamber and rotating and locking the bolt to restart the sequence.

The problems with this particular system are multiple. It is dumping combustion byproduct – “dirt” – into the same place it feeds ammunition from. This leaves a lot of carbon buildup over time and can create function problems when not maintained regularly. The lower receiver and its trigger group are often heavily soiled from this gas system and it is compounded numerous times over when combined with the use of a sound suppressor. Due to the carbon, unburned powder and extra heat following the path of least resistance, the extra back pressure created with the use of a silencer leaves more debris than normal and blowback is often an unpleasant effect inflicted on the shooter. On top of the maintenance issue, which in the recreational shooting world should be a no-brainer, is an issue not often spoken about. As indicated before, the additional debris is carried back into the action of the gun and it is carried by very hot gas. It has been suggested by some people that the effect of these hot gasses under heavier than normal shooting conditions could cause metal temperament problems over time. A heavy influx of heating and cooling could create some structural problems with extremely heavy use.

There are several systems that now use a gas piston system in place of the direct impingement system and Small Arms Review has covered several of them in the past. In the last two years we have examined the HK416 System, the POF P-416 System and just recently, the Colt LE1020 Advanced Law Enforcement Carbine. Fairly recently, Ares Defense introduced their GSR-35 Black Lightning system, which is a drop-in piston kit that takes the place of the original gas tube and bolt carrier. Leitner-Wise Rifle Company (www.lwrifles.com) also specializes in a piston system however we have not had the opportunity to evaluate it yet. While the concept is certainly nothing new, (Colt experimented with a piston system in the 1960s, and there are many other examples pre-dating that) its time certainly seems to have come and it appears to be here to stay.

Other than a brief amount of time spent working with an early “Rhino System” in the early 1990s, of all the systems mentioned above, this writer only has an extensive amount of time on the POF P-416 system at this point. Other SAR contributors have extensive trigger time on the HK416, and will cover other systems in the future. On the POF system that I have tested, there are definite advantages that have been witnessed, primarily the number of rounds it is able to run with little or no maintenance with no malfunctions. The POF P-416 utilizes C.R.O.S. (Corrosion Resistant Operating System) where their major components are impregnated with silicon nickel creating an incredibly slick surface. After firing several thousand rounds, the surface easily wipes clean with only a dry cloth, and after almost 20,000 rounds in one particular test unit there is no visible wear on any of the coated parts.

During initial testing the system was fired in excess of 9,000 rounds with no maintenance or lubrication of any kind and when it was finally cleaned because we thought there was a single failure to feed, ending the endurance test, it was later found that it was a faulty magazine creating the feeding problem and not the gun itself. Another factor that assists the P-416 system in functioning so well under harsh treatment is the fact that there are no gas rings necessary since there is no actual gas pushed back into the bolt carrier. This seems to translate into a firearm that will operate in a harsher environment due to much lighter tolerances. Without the presence of gas rings creating a seal between the bolt and bolt carrier, everything moves much smoother and is less meticulous in its typically tight tolerances.

If there is an immediately noticeable advantage in this particular gas piston system it is durability. On top of the several thousand rounds fired with no maintenance except for the initial cleaning after the perceived stoppage, many of them have been in a succession so rapid that it would have been certain failure for a direct impingement system; melting the gas tube and ending the testing very early on. After years of testing black rifles, the author has a collection of failed gas tubes, many resembling spaghetti found lying on top of the barrel after reaching the point of failure. If there are any immediate disadvantages of this gas piston system over a direct impingement system, this author has not yet noticed them.

Now Left Can Be Right

A fantastic example of how the civilian market often takes its own direction and even has the potential to influence the military marketplace is a manufacturer from New Britain Connecticut named Stag Arms, LLC. (www.stagarms.com). Founded in May of 2003, Stag decided to cater to a percentage of the market who had been all but ignored for years. They completely redesigned the upper receiver, bolt and bolt carrier to eject from the left, specifically for left-handed shooters. Featured in the March 2006 (Vol. 9, No. 6) issue of Small Arms Review, southpaws will never again have to depend on a brass deflector keeping hot brass from hitting them or crossing their line of fire.

The Future

It is the versatility of the AR-15/M16 that has allowed it to adapt and thrive in so many differing environments and it is the modularity of the system that is a direct contributor to its survival and evolution. There are a few companies that are addressing this in ways that could never have been originally conceived 40 years ago and will lead the way into a long future for the black rifle.

MGI (www.mgimilitary.com) has been in the black rifle business for decades. Their upgrades have been chronicled in the pages of Small Arms Review several times including their Rate Reducing Buffer – May 2004 (Vol. 7, No. 8), The QCB Upper Receiver – December 2004 (Vol. 8, No. 3) and most recently The Hydra Modular Weapon System – May 2007 (Vol. 10, No. 8). With such versatility as a quick-change barrel upper receiver that requires no tools and works with original factory barrels, changes in length, style and caliber have never been faster, easier or less expensive. The Marck-15 Lower Receiver with interchangeable magazine wells, again with no tools, allows the correct magazine to be used to coincide with the caliber being fired. For example, if you are utilizing a 7.62×37 barrel and bolt, you can use the AK mag-well and utilize standard AK47 magazines. This ensures the correct feed and presentation rather than redesigning a new magazine around an existing space and angle. Mags are inexpensive, available and reliable. Next in the works is a 9mm SMG mag-well that will utilize the factory Colt 9mm SMG magazines. Several new offerings are in the pipeline, some certain to be out even before this magazine hits the newsstand.

Cobb Manufacturing (www.cobb50.com) has a line of rifles called the MCR (Multi Caliber Rifle) and it is based on the design characteristics of the AR-15, just a little bigger. The MCR is a semiautomatic, gas operated system that can be chambered in a long list of calibers from 9mm to 338 Lapua, designed originally for the SCAR rifle program. They are far from newcomers to the industry and have been dealing with such innovative firearms as the .50 BMG FA50 and BA50 for several years. Teamed up with top-line suppressor manufacturers their systems are well made and versatile.

With the “feeding” frenzy a constant issue as discussed previously, we expect to see upgrades and alterations to this portion of the weapon system as long as it is in use. Just before finishing this article the author received what is perhaps the latest offering to the high-capacity quest to evaluate for a future article. It is the CL-Mag from Armatac Industries, Inc. (www.armatac.com). Resembling the Beta C-MAG in shape, the CL-Mag is manufactured from aircraft aluminum and holds 150 rounds of 5.56x45mm. Finished in a hard coat type III anodized finish, it is intended to work in all AR-15/M16 variants. We are anxious to proceed with testing this new feeding system in the near future.

Conclusion

Since there is really nothing to compare the popularity of this unique weapon system to, with its longevity in both military and civilian applications, it is the opinion of this writer that the sheer ability to act as a chameleon and adapt to almost every environment is the life force behind its ever growing popularity. It has to be noted that many of the upgrades and enhancements are civilian based ideas with no military spec sheet giving them direction. Some of these ideas and items can be looked at as simply “fun” and that is an important aspect of shooting that some of us who are a little too hung up on being “professionals” tend to overlook a little too often. Not everything that is discovered or tested has to have an adrenaline soaked special operations application in mind. Some of the best gear for our professional applications stands a chance of starting out as a light-hearted civilian product, just because it is looked at and designed with fresh, new, untainted eyes. Some of the greatest design innovations this writer has witnessed have come from challenges from people who specifically stated that in their professional opinion something couldn’t be done.

With an ever-changing requirement for the ultimate weapon system in this unpredictable War on Terror, if any weapon stands the test of time it is the AR-15/M16. With a virtual flood of new accessories, upgrades, calibers, finishes, furniture and design enhancements being introduced at breakneck speed, this writer has a hard time even thinking of the day where the black rifle or some form of it is not going to be the basis for our primary service weapon for at least 40 more years.

Author’s Note: While this article started out to be a short overview of the AR-15/M16 and its longevity, it soon became obvious that it could not be done in just a few words. The system is too complex and the changes, alterations and upgrades are far too numerous to simply skim over and condense. Unfortunately, due to space constraints, it had to end somewhere and we were not able to include every single company that offers firearms and accessories related to this weapon system. They are far too numerous, and even a quick glance through the pages of Small Arms Review will reveal several more businesses who specialize in parts and accessories for the black rifle. It is not our intention to promote anyone in particular while leaving anyone else out, nor should either be misconstrued as an endorsement or lack of such in the latter case. We would be happy to put together a condensed Black Rifle Buyers Guide listing every business related to this system in the future, but had no room to so in this article.

At the Arizona State Fairgrounds during the SAR Show in 2003, Frank Desomma of Patriot Ordnance Factory (POF) showed an early prototype of what would eventually become the P-416 Weapons System; billed as the future of M16 weapons systems. He continued to work and refine his new system, and in early 2006 he sent SAR two semiautomatic production models for evaluation: one with a 9.25 inch barrel and the other with a 16-inch barrel.

The POF P-416 with C.R.O.S. (Corrosion Resistant Operating System) is an op-rod and gas piston driven M16 weapons system enhancement. It has completely eliminated the traditional gas tube and the unpopular issues associated with it. It has been stated many times that the greatest flaw of the M16 family of firearms may be that it forces gas and debris into the receiver via the gas tube, directly above the magazine. This is effectively dumping the waste in the same area the feeding takes place. The P-416 appears to completely address this design feature by capturing everything in the area of the gas block and not allowing residual debris to transfer into the feed mechanism.

In a standard M16, as the bullet passes the gas block (doubling as the front sight), residual gasses are channeled into the gas port. The gasses are transferred through the gas tube into the bolt carrier through the bolt key. The pressure created by these gasses causes the rearward travel of the bolt carrier, unlocking the bolt and ejecting the fired case. With this transfer of gas, necessary for this system to function, comes other undesirable variables including unburned propellant debris and heat. With a brief look inside the operating mechanism after firing several magazines, the residual debris quickly become apparent. The extra heat transferred through the gas tube may be immediately noticeable with heavy sustained fire or may take a long time to create potential problems culminating with gas tube malfunctions ranging from gas port erosion problems to simple excessive use malfunctions.

The P-416 operates like a standard M16 in that the gas behind the exiting bullet is directed through a port into the gas block, but that is where the similarities in the gas system end. In the P-416, the gasses contact a piston just behind the gas block and cause it to travel to the rear. The gas piston pushes the op-rod which in turn pushes the bolt carrier rearward. Due to the fact that the op-rod is solid, carries no gas and only travels rearward itself, all residual gasses and debris are dissipated in the area of the gas piston, never reaching the receiver area. The inside of the receiver is not coated with flakes of powder and a film of carbon as is commonly the case with standard M16 variants.

Some people believe that the excessive heat transferred through the gas tube during heavy fire can create a potential for serious problems, even if not immediately apparent. With the bolt carrier and bolt reaching high temperatures and cooling over and over, it may create a problem with the strength of the metal causing it to become brittle over time. Due to the piston and op-rod design of the P-416, these concerns are addressed by capturing the residual heat and debris in and around the gas block, and not allowing their transfer back inside the receiver.

Since the bolt carrier is no longer utilized as a “gas trap” and responsible for the sealing of the moving gasses, the gas rings are removed from the bolt and the gas key was replaced with a special solid key that, on early guns, is bolted into a milled slot in the new carrier. Later bolt carriers in this system are 1-piece units where the “key” is machined out of the same material as the carrier thus forming one single piece. This will further the life of the unit by providing an even stronger impact area for the op-rod and ensuring a strait push rearward to avoid flex problems that were encountered on earlier prototype units. The bolt and carrier of the P-416 are both chrome plated and heat treated to Mil Spec.

The absence of the gas rings on the bolt serves an additional purpose of extremely reducing the amount of friction in the recoil system. The gas rings on a standard M16 bolt and bolt carrier need to create a seal so that the gas pressure is adequate to operate the recoil system. To create this gas seal, there is a necessary metal-to-metal contact that causes the friction. This is no longer necessary with the P-416 system. Upon pulling the charging handle the first few times it is obvious that the system in this aspect is much “looser” than a traditional M16.

POF has taken advantage of this reduced friction property and have compounded it by adding a coating of Silicon Nickel to the inside of the upper receiver and the interior surface of the charging handle. This creates an extremely slippery surface and one that seems quite impenetrable by typical debris such as carbon. It also seems to have a very low wear factor based on the results of our testing with the firearms provided.

Strictly as an endurance test, the 9.25-inch barrel version of the P-416 we were provided with had already fired in excess of 5,000 rounds with no cleaning or lubrication. When we received the gun it was obviously dirty upon the initial inspection. In a telephone discussion with Frank Desomma, he laughed and said that since we were going to test one of his units for endurance, he was confident enough in its abilities that he wanted to send one that had already been used extensively instead of something pretty and off the shelf. When he said how many rounds had already been fired through it, the gun was disassembled for inspection. Though the inside of the receivers were amazingly clean, the amount of built-up carbon inside the Krink-style muzzle brake gave all the evidence needed about the number of rounds that had been fired. All of a sudden the number 5,000 did not seem so high anymore.

As further evidence of the number of rounds already fired, there was no way to remove the gas plug with normal hand and finger pressure due to the carbon buildup around the outside of the plug. The detent could be depressed and rotated to the position necessary to remove it, but it would not budge by pulling it forward. Being assured that no tools would be necessary to take it apart, it was time to start improvising. It was noticed that when the charging handle retracted the bolt carrier and the carrier was allowed to slam home, the op-rod would contact the gas piston which would in turn push on the gas plug. After dropping the bolt carrier in this manner several times, the gas plug was out far enough to get a better grip on it and pull the remainder of the way out. The gas piston and op-rod easily dropped out just by tilting the muzzle down with absolutely no resistance.

This excessive carbon around the gas plug was mentioned to Desomma due to the extreme number of rounds since any type of maintainance had been conducted. Desomma said the lugs of the gas plug will be chromed like the barrel of the plug currently is to reduce friction; but we would certainly find that under normal heavy use, removal would not be a problem. He was correct. No tools were necessary to remove the gas plug at any time and he insisted that the manner we used to remove it would not compromise the system in any way.

The upper receiver was reassembled without cleaning or lubricating of any kind, and the lower receiver we were provided with underwent a little makeover. If we were going to do a true SAR endurance test it would be completed in full auto on the correct lower. A few hours in the shop and a Form 2 later, we were ready to rock and roll.

Given that we had a dirty gun to start with, it was decided to jump right into the shooting phase and do some photography after finishing and cleaning up the parts a little. It was at this time we decided to run several data strings to gather information about cyclic rates, chamber temperatures and muzzle velocities while continuing to severely add to the number of rounds fired. The 9.25-inch barrel seemed to lose around 400 fps when compared to the 16-inch version and a little over 250fps compared to a 14.5-inch variant.

The chamber area temperatures in the P-416 ran surprisingly low, between 80°-92°F after 20-round and 30-round bursts with little time for cooling in between. The standard M16 gas system averaged between 86°F and 120°F under the same conditions. With temperatures being a primary consideration in the P-416 system, POF has designed a special barrel nut that can be used in conjunction with their Predator Rail System that doubles as a heat sink. Made completely from 7075 T-6 aluminum, it will provide a larger surface area and utilizes cooling fins. This barrel nut will draw the heat from the chamber area faster than usual, creating a cooler operating temperature. This proprietary barrel nut also serves to provide strength and rigidity to the rail system by increasing the mass of the area where the upper receiver connects with the system.

Rates of fire were measured using 3 different buffers. We used the MGI Military Rate Reducing Buffer, the Enidine AR-restor Hydraulic Recoil Buffer and a standard factory buffer. The 16-inch P-416 ran extremely slow and was very controllable with all buffer systems. The muzzle rise was barely noticeable with the both the MGI and the Enidine buffer and was slow enough to be at the point where you could actually count the shots. The MGI averaged slightly fewer than 550 rounds per minute. The Enidine buffer averaged just over 660 rpm and with a factory buffer it was still averaging only 690 rpm. These numbers were all recorded with a standard A2 Flash hider. With any M16 rifle system, the use of accessories such as silencers and certain muzzle brakes can greatly affect the rate of fire. For comparison, we repeated the tests with a Gemtech M4-02 silencer and the increase in rate of fire due to the extra backpressure averaged 279 rpm. We found that using the Krink-style muzzle brake on the 9.25-inch POF-416 even increased the rate of fire by an average of 50 rpm.

The Gas Piston in the 16-inch variant of the P-416 has a reversible feature allowing the operator to compensate for devices like silencers that typically increase the cyclic rates. In normal operating mode the piston is inserted with the 3-groove end towards the muzzle. When silencers or other gas restricting devices are used, the piston can be reversed and inserted with the 2-groove end towards the muzzle. In our ROF tests we found that this allowed the rate of fire to remain a little slower with these devices. When we tested this gas piston change, the rate of fire we recorded with the 3-groove end to the front and a Vortex flash hider averaged 588 rounds per minute utilizing an MGI Rate Reducing Buffer. When the Gemtech M4-02 silencer was added the rate of fire immediately jumped to 851 rpm. This is a difference of 263 rpm. When the gas piston was removed and reversed, the cyclic rate instantly dropped to 781 rpm. Simply reversing the gas piston brought the rate of fire down by 70 rpm to a more comfortable 781 rpm. It is important to be noted that the system will not operate at all with the gas piston in this position with standard flash hiders. When the Gemtech M4-02 silencer was removed and the Vortex flash hider was reinstalled, we could not get the P416 to function for more than 3 rounds without a failure to eject.

The rate of fire in the 9.25-inch system was substantially higher than the 16-inch system with a recorded low ROF of 801 rpm with the MGI buffer and a high of 1,108 with a factory buffer. We did not test any sound suppressors on the 9.25-inch system, as many suppressor manufacturers do not recommend use on barrels so short.

The 9.25-inch P-416 system made several trips to the range during the testing period. It was handed to several shooters who were given a briefing on the operating system and they were invited to shoot it all they wanted. Not surprising, several people took advantage of the opportunity. Since we explained that it was an endurance test as well as a standard T&E, several people fired full, 100-round Beta C-Mags, most in a single burst. We lost count of the exact number of rounds fired due to the massive influx of “extra ammunition” fed through it by other shooters but we recorded almost 4,000 more rounds of assorted ammunition fired from our own supply before the gun finally had a failure to eject and was stripped and cleaned. That brings the total to well over 9,000 rounds without cleaning or lubrication of any kind. A simple brushing of the chamber may have been adequate enough to keep going but we used this time as an occasion to end the endurance phase of the testing. The only malfunction encountered during the testing was a broken hammer pin mistakenly utilized when the author installed the full auto parts after converting the lower receiver to fully automatic. The pin was replaced with the correct one and not a single malfunction was recorded until the final failure to eject where we decided to end the test and clean the gun.

The gun was disassembled and thoroughly cleaned. The chamber area was indeed very dirty and there was a little residue in and around the area of the locking lugs. The inside of the upper receiver just wiped clean with a dry cloth exposing the shiny nickel finish showing no signs of wear. The lower receiver had little debris to clean up; mostly a thin film that looked like it had been subject to a heavy layer of smoke for a long period of time. After it was disassembled, cleaned and photographed, it was reassembled and finally lightly lubricated. Every trip to the range since then, it has again been fired extensively and has yet to malfunction again.

The Krink muzzle brake supplied on the 9.25-inch system was well received by everyone who used it. This particular brake had been described in the past as a flash hider, and that statement could not be further from the truth; at least in this barrel length and caliber combination. It was quieter to the shooter than to those observing and seemed to be fairly effective in reducing recoil but it did nothing to hide the flash. Quite the contrary, this brake seems to enhance the flash and force it forward as it does the sound. A short-barreled 5.56x45mm typically has a large diameter flash signature with an ineffective flash hider or in the absence of one. The flash in this configuration is clearly long and narrow creating quite a spectacle even in bright daylight.

The Predator rail system was utilized on both test rifles although not necessary for the P-416 gas piston system. The Predator Rail System is a single unit that acts as an extension of a standard flat top upper receiver. It allows the barrel to remain completely free-floating and under no stress from optics and accessories. It is also completely removable allowing the shooter to access the barrel and the gas system. On the 9.25-inch version we used the P-4X and on the 16-inch version we used the P-12X. Just before going to print we received a newer P-12SX, which has a longer bottom rail. The weight of the P-4X is only .66 pounds while the P-12X weighs only 1.15 pounds. Several variants of the Predator Rail System as well as many of the optional accessories we utilized during this article are available directly from POF. Full technical specifications and pricing is available on their website at www.pof-usa.com.

Summary

POF has created a frontrunner with this system. From the well thought-out gas piston, op-rod and carrier group to the impressive Predator rail system, it is a winner in every aspect. The only suggestion to improve upon the system would be the addition of a small tool to assist in removing the gas plug after heavy use, though this may be rectified by the intended hard chroming the lug area of the gas plug as previously discussed.

The front sight utilized with the 9.25-inch P-416 is another effective design from POF. It is called the FTA (Fast Target Acquisition) 2005 Sight and was well received by all who handled the firearm. It has a “no snag” feature due to the sight post being completely enclosed. The most noticeable benefit during our testing was the speed and effectiveness of the sight and the ability to stay on target even under long bursts of full automatic fire. The post in the center of the circle draws your eye into the center if it starts to stray due to the vibration or normal muzzle rise. An additional benefit to those who would use this system for tactical applications is the hood cannot be mistaken for the sight post under poor lighting, or during the necessity for extremely fast target acquisition. The front sight post stands alone very clearly. The sight is removable if the use of optics without its assistance is desired or it may be used in combination with a zero magnification electronic sight. We found both applications were comfortable and easy.

Since arriving for initial testing, the little 9.25-inch system has been the authors “go to” gun and it looks like that will continue. It is extremely well made, very controllable, looks great and functions even better. With the ability to perform through several thousands of varied brands of ammunition throughout several range conditions and continue to run without a hiccup, it is certainly a winner. Operators who must utilize weapons systems in varied conditions should seriously consider evaluating this system for team use. Their reliability factor can certainly be advantageous for times when maintainance, cleaning and lubrication are considered a luxury.

The compact size of the system gives the user an excellent PDW. With a 9.25-inch barrel and overall length of only 27 inches, it is not much larger than an Uzi SMG with the stock extended, which is only 1-inch shorter. The ballistics of the P-416 combined with availability of dependable high capacity magazines and a sturdy rail system capable of numerous tasks should make this a serious contender in any evaluation.

This test systems inclusion of the Krink” muzzle brake only added to the “fun factor” and for someone who loves to shoot recreationally, that has to play an important role. It has been my experience that any fan of the Black Rifle who has the pleasure to try this system will soon wish to acquire one.

The Predator Rail System

The P-415 / P-416 firearms and upper receivers are available with the Predator rail system. This unique system is machined from a solid piece of aluminum and provides an excellent platform for mounting optics, grips, lights, bipods and any of numerous other accessories. The barrel remains completely free-floating and the proprietary barrel nut even works as a heat sink to keep chamber and barrel temperatures cooler than with standard upper receivers by drawing heat away from the chamber. 1) To disassemble the Predator Rail System first you must remove the two Allen-head screws located on the sides of the system parallel with the barrel nut. These are located at the 3 o’clock and 9 o’clock positions. (Pred1) 2)Next remove the two Allen-head screws located on the top of the system at the 12 o’clock position directly above the barrel nut. After removing those top screws you will notice there are two more screws UNDER the first ones. The second set of screws are holding the barrel nut spacer in place and must also be removed as well. (Pred3) 3) Remove the Allen-head screw at the top rear of the system immediately above the charging handle. (Pred4) 4At this point grasp the upper receiver in the forward assist area and slide the Predator rail system to the front. (Pred5). 5) The upper receiver will now be separated from the Predator rail system Reassemble in the reverse order. 6)You will need to realign the barrel nut spacer (A in Pred6) over the barrel nut (B in Pred6) when you begin.

Technical Specs
POF P-416

Weapon System
Rate of Fire
9.25-inch P-416
14-inch M4 16-inch P-416

Factory Buffer 968 rpm 855 rpm 690 rpm

MGI Buffer 831 rpm 658 rpm 546 rpm

Enidine Buffer 768 rpm 738 rpm 664 rpm

Muzzle Velocity 2,286 fps 2,552 fps 2,688 fps

All testing utilized 62gr Wolf FMJ Polyformance Ammunition. Data recorded with PACT MK IV Timer and Chronograph.

Sources

POF-USA
Dept. SAR
23623 N. 67th Ave.
Glendale, AZ 85310
Phone: (623) 561-9572
Fax: (623) 321-1680
www.pof-usa.com

Wolf Performance Ammunition
Dept. SAR
1125 North Lance Lane
Anaheim, CA 92086
Phone: (888) 757-WOLF
Fax: (714) 632-9232
www.wolfammo.com

Gemtech
Dept. SAR
P.O. Box 140618
Boise, ID 83714
Phone: (208) 939-7222
Fax: (208) 939-7804
www.gem-tech.com

PACT, Inc.
Dept. SAR
P.O. Box 535025
Grand Prairie, TX 75053
Phone: (800) 722-8462
www.pact.com