Ever since the change over from the 7.62x51mm to the current 5.56x45mm there has been controversy between two fundamental schools of thought on what a military cartridge should be. The United States military can be summed up in one word: tradition. In the 1960s, that tradition clouded the vision that a new dawn of small arms development in both concept, mechanics and ammunition had come. Still entrenched in the “one shot, one kill” mentality, our soldiers were sent into combat in Vietnam with the M14 which many considered to be an inferior weapon to the AK47 assault rifle that the enemy used. The enemy were able to lay controlled large volume of automatic fire on positions which, in a meeting engagement, will win you a fight. Our soldiers were equipped with a heavy recoil rifle that was impossible to control on fully-automatic. The accuracy was of no use because the enemy could not be seen.

With much trepidation, the military adopted the AR-15 rifle destined to become the M16/M16A1. A new age of small caliber high velocity cartridges gave way to providing an individual soldier with firepower he had never had before. The 5.56x45mm cartridge utilizing a .224 diameter 55-grain full metal jacketed bullet proved to be a great asset to the American fighting man with the ability to have a lightweight rifle that was completely controllable on fully-automatic fire and the soldier could carry more than twice the combat load with an M16 than he could with the heavy M14 rifle.

The Third Generation M16A2 and M855 Ball

With the product improvements of the M16A2 the weapon system was enhanced. Due to the heavier 62-grain bullet, 1 turn in 7 inch rifling twist and new fully adjustable rear sight, both penetration and long range accuracy were enhanced. However, the culprit of the future problems with ammunition terminal performance would come from the ammunition, the M855 Ball.

The M855 Ball is a three piece bullet consisting of a copper jacket, lead plug and a steel penetrator core in the tip. This bullet was designed for a machine gun, not a rifle. With the onset of the Global War on Terrorism, terminal deficiencies were found using M855 Ball, particularly in M4 carbines, when striking thin, malnourished, Taliban and Iraqi soldiers. There was a serious inconsistency in at what point the bullet would yaw and splinter. Some lots of ammunition would penetrate only slightly within inches and yaw and splinter. Others would go straight through and never yaw nor splinter. This caused serous knockdown problems particularly with the decreased velocity of 14.5 inch carbine barrel.

A solution put forth by the United States Special Operations Command (SOCOM) was the creation of a new and improved 5.56x45mm cartridge that would increase long range accuracy and terminal performance with consistency. Accuracy is seriously degraded in the M16A2/A4/M4 due to the inherent characteristics of the M855 bullet. The penetrator core degrades accuracy and if not manufactured properly, the center of gravity will be off causing the bullet to become a “flyer.” Additionally, in the area of terminal performance, there was no consistency from lot to lot on what exactly it would do upon hitting a human target.

The answer was the Mk 262 MOD 1 cartridge that SOCOM adopted. This is a Sierra 77-grain open tip match bullet loaded by Black Hills. This is undoubtedly the most effective 5.56x45mm military cartridge in the world manufactured to match grade specifications with combat reliability. The long range accuracy was drastically increased and its terminal performance enhanced. This new projectile works well regardless of the type of target and performs considerably better on human targets in all known distances and conditions. This round is used almost exclusively by SOCOM operators in their M4A1 carbines and Mk12 rifles. This solution satisfied most of the SOCOM operators: except for one.

The 6.8x43mm REM SPC

The 5th Special Forces, particularly MSG Steve Holland, felt that there was still room for improvement. The concept was not original. The U.S. military experimented with the possibility of the 6mm caliber projectile being the ideal compromise of accuracy, range and terminal performance. In the late 1970s the concept was abandoned in favor of the 5.56x45mm battle rifle.

With the assistance of the U.S. Army Marksmanship Unit, Holland came up with a concept for a 6mm cartridge that could be fired in the M4 platform. The starting point was the .30 Remington cartridge which is merely a rimless .30-30 Win. round. It was trimmed and resized to accept a 6.8mm projectile. This concept, along with the hand-loaded experimental ammunition and CAD drawings went to Remington Arms. Remington wanted to aid in the Global War on Terrorism so they took on the task of developing the ammunition.

The 6.8mm REM SPC cartridge has been mostly a myth for the last few years due to the fact it has been developed quietly and kept proprietary. No ammunition has been made as of this writing in large quantities due to the fact the ammunition is being perfected before it will be shipped. Remington has reported three small runs of ammunition including ball and match grade ammunition. Hornady has also produced some loads in this new caliber.

The Firearms

Prototype rifles were manufactured by Precision Reflex, Inc. (PRI). Dave Dunlap assembled upper receivers with free floating handguards or A.R.M.S., Inc. SIR systems and the OPSINC silencer and muzzle break. Dunlap also was charged with designing the magazine which is different from the standard 5.56x45mm magazine. Currently, PRI has been the only producer of 6.8x43mm Rem SPC magazines. PRI also produces complete upper receivers chambered in the 6.8x43mm Rem SPC cartridge.

The Barrett M648

At the 2004 SHOT Show, Ronnie Barrett unveiled a new product line: his M648. This company, dedicated to .50 BMG caliber specialized weapons, introduced the first production 6.8x43mm Rem SPC firearm and has taken the lead on this project. While the cartridge is still technically under development (to be more correct would be to say “tweaked”), Barrett has teamed up with Peter Forras to work with Remington to optimize the weapon and cartridge. Forras has spent much time down at Remington working with them to perfect the 6.8x43mm cartridge.

The rifle has been based on the standard M16-platform. Barrett offers the rifle in both commercial and law enforcement/military configurations. The “bells and whistles” are the same for both versions, the only real difference is the use of selective fire, flash suppressors, bayonet lugs and telescopic stock on the law enforcement/military models.

The weapon as offered uses a mid-length gas system developed by Mark Westrom of ArmaLite, Inc. This mid length gas system changes the location of the gas port by placing it further forward than the carbine and slightly behind the rifle. This gives two major advantages: reliability and durability. By putting more distance between the bolt carrier and gas port, lower port pressures are created resulting in the bolt assembly’s velocity being slower. This increases reliability in extraction as well as extending the life of the bolt and some of the trigger components.

The barrel is manufactured by Fred Fedderson. This 1 turn in 10 inch twist barrel is chrome plated and is currently available in 16 inch length only. Barrett has plans on offering 12 and 20 inch barrels in the near future. The commercial version has a muzzle check similar to the one used by ArmaLite, Inc. The law enforcement/military versions use the standard M16-style muzzle break/compensator

The M648 gas block utilizes a folding front sight assembly. This assembly was designed by Barrett. On the law enforcement/military version, there is a threaded collet on the edge of the gas bock to install the silencer.

The Mid-Length SIR System

The A.R.M.S. Inc. SIR (Selective Integrated Rail) system developed by Richard Swan is the solution for many problems associated with military use of this type of weapon system. The SIR system is a free-floating handguard assembly that attaches to the carrying handle by a sleeve that goes on top of the rail (thus protecting it) as well as directly to the barrel nut. This give an extended top rail that runs the entire length of the upper receiver to the front sight assembly. There are four Mil-Std 1913 rails that enable optics, laser, flashlights and whatever other accessories that may be needed for the rifle with no effect on the barrel and its performance.

Free floating a military weapon has many benefits. First would be accuracy. With nothing impeding on the harmonics of the barrel, better uniform accuracy is achieved. Additionally, the barrel remains cooler as there is significantly better air circulation enabling the weapon to fire longer on full automatic fire. Another benefit, particularly with a hot barrel, pulling down on a vertical fore grip will not cause the barrel to bend or droop. The SIR system may also have a M203 grenade launcher attached to it. All the current models of the M648 feature the A.R.M.S. Inc. SIR system as well as the ARMS #40 L emergency flip-up backup sight.

The Bolt

The bolt carrier is standard M16/AR-15. The difference lies in the bolt itself. The bolt was designed by Chris Barrett and is manufactured by Lewis Machine & Tool (LMT). The bolt uses the trademark dual extractor spring “lobster tail” extractor manufactured by LMT as it is more durable and reliable. The bolt has other similarities to the LMT Enhanced bolt but Barrett made some changes in materials and specifications specifically for the M648. The bolt has a nickel plating on it.

Configurations

The M648 comes as a full weapon with fixed rifle stock as well as selective fire carbine lower receiver with the telescopic buttstock. The system is also sold as an upgrade or a conversion kit which will include the entire upper receiver assembly and magazine. The conversions can be obtained with either selective fire bolt carriers or semiautomatic only. It should be noted that when putting a conversion on a standard selective fire carbine lower receiver, the “H” buffer should be used. This is the buffer with two steel weights and one tungsten. If the standard three steel weight buffer is used the carbine may experience bolt carrier bounce resulting in light strikes on full automatic. This is not an issue with the full length rifle selective fire lower receiver. Semiautomatic guns can use either due to the bolt group will have sufficient time to lock before the next shot is fired. There has been some discussion about Barrett eventually coming out with a piston driven mechanism for this weapon system.

Shooting Impressions

The rifle received for testing was a law enforcement/military upper receiver with a standard semiautomatic only lower receiver. The author’s own Colt M4 full automatic carbine lower was used for full automatic testing. The semi-automatic only lower receiver was equipped with an LMT two-stage match grade trigger. The optics used were the M68 Aim Point Comp II, EOTech holographic sight as well as the standard backup sights. Approximately 700 rounds were fired in total in both semiautomatic for accuracy as well as fully automatic for functionality. The magazine used was a PRI made 28-round steel magazine. The ammunition was manufactured by Remington.

Fully-automatic tests were conducted in close quarter battle conditions. Targets ranged from 5 to 25 meters. The cyclic rate was about the same as the standard M4 carbine and recoil was really not that much more. There was no problem controlling the weapon. The EOTech sight made shooting easier allowing both eyes to remain open increasing speed and accuracy. By adjusting the brightness of the sight, it was useful for both close tactical work as well as short range sniping.

Conclusions

The 6.8mm Rem SPC is without a doubt an improvement over the existing 5.56x45mm for military use. But the question is, how much better? The cartridge unfortunately has a very steep uphill battle ahead of it once the military community gets a hold of it. The weapon itself is not an issue. The M16-based design is well proven. But in order for SOCOM in particular to adopt such a cartridge for use will be a gigantic undertaking. First and foremost it has to be more than better, it will have to be drastically better and offer a large advantage. Second, and perhaps the most critical, will be logistics. The cartridge will be at best used by SOCOM operators and them alone. From a logistical standpoint, adding a new cartridge into inventory, in particular one nobody else in the service uses, can cause serious problems. Once SOCOM operators are deployed they become part of the unit they are assigned and along with that goes their supply. Having non-compatible ammunition can put the operators at risk given they do not have re-supply specific to them.

The Barrett M648 and 6.8x43mm Rem SPC ammunition performed flawlessly and accurately. Barrett has not been too quick to go into production due to the fact they have waited until the development of the rifle and ammunition was completed insuring their customers get a final production weapon and not a semi-prototype. As of this writing, after more than three years of advertising and manufacturing of barrels to fire this new cartridge, the ammunition has yet to be completed and put into full production. This weapon and cartridge will undoubtedly find a following in law enforcement and commercial shooters and competitors. As far as the military use of this weapons system, only time will tell.

Since the introduction of the Colt Commando and XM177-series carbines, the U.S. military has had a need for a compact version of the M16, the longest serving small arm in U.S. history. Even though never officially adopted, these carbines saw extensive use in every theater of operations the U.S. and her allies were in.

In 1985, U.S. Government contract DAAA21-85-C-0192 was awarded to Colt for the development of the XM4 carbine, the first general-purpose carbine since World War 2. The contract had very specific wording in regards to parts commonality with the newly adopted M16A2 rifle. Particular effort was made to keep as high of a number of parts compatible with the M16A2 as possible. As first envisioned, the XM4 was to be used for troops who could not carry a rifle but needed more firepower than a handgun. It was to fill the same role as that of the M1 Carbine.

Parts Commonality as Defined by DAAA21-85-C-0192

Specifically stated in the requirements was that the carbine would utilize the newly adopted M855 ball cartridge as well as be functional with existing M193 ball ammunition. The barrel will have the same 1 turn in 7 inch rifling twist as the M16A2 and be 14.5 inches in length. The barrel must be made to accept the current MILES shooting simulation equipment as well as utilize the M16A2 compensator. The carbine must have the 3-round burst limiter of the M16A2. The polymer furniture must be made of the same high impact material as the stock, pistol grip and hand guards of the M16A2. The upper and lower receivers are to be the same as the M16A2 amongst many others.

The parts commonality requirement was troublesome to Colt engineers but they understood the government’s position. With over 7 million M16-family of weapons in service at the time, they did not want to make any dramatic changes to an already proven design. Owing to the different operating characteristics of the carbine, Colt felt there should be some changes. Due to the gas port being so much closer to the bolt, higher pressures existed in effect, significantly increasing the cyclic rate of fire. This caused issues with bolts breaking, bolt carrier bounce, failures to extract as well as feed. However, the government was very much stuck on interchangeability over durability/reliability. Colt engineers felt that a redesign of the bolt and barrel extension would significantly enhance the carbine’s performance but this would have been a major violation of the interchangeability requirement.

During the development phase, Colt engineers found certain changes that must be made for the carbine to function reliably. One of the first improvements made to the XM4 was to correct failure to feed. Due to the shape of the M855 bullet and the higher cyclic rate, the cartridge would stall where the barrel extension met the upper receiver. To correct this, both feed ramps were extended on the barrel extension as well as the upper receiver. After much experimenting with buffer designs, a new buffer was implemented to combat the bolt carrier bounce issues during burst fire. Because of the higher cyclic rate, as the bolt carrier moved forward, the bolt would lock releasing the automatic sear in turn releasing the hammer to strike the firing pin. But at that moment when the carrier struck the barrel extension it would bounce back just enough to disallow the firing pin enough clearance to strike the primer. Thus, a new buffer was adopted for use in the XM4. This new buffer (H) would remove one of the steel weights and replace it with a weight made of tungsten weighing nearly twice that of the standard steel weight. This extra mass slowed down the cyclic rate on the closing stroke eliminating the problem.

Another requirement was to have an increase in the carbine’s ability to dissipate heat, keeping the shooters hand cooler during firing/handling under normal conditions. To answer, Colt’s Henry Tatro developed a hand guard (U.S. Patent No. 4,663,875) with double heat shields.

Several other parts were modified to increase reliability such as the burst cam, stock and ejection port dust cover. The first production M4 carbines were delivered with standard M16A2 fully adjustable rear sights. This was soon to be replaced with the Mil-Std-1913 flat top upper receiver. The M4A1 carbine would only be issued with the flat top upper.

The true “heart and soul” of the M4 carbine is the Mil-Std-1913 flat top upper receiver. The Colt/ARMS, Inc. designed flat top upper receiver and dovetail is the modularity of the carbine. This enabled the use of an entire new generation of advanced optics including reflex sights, thermal sights, optical sights as well as night vision. The dovetail enabled optics to be mounted at a comfortable eye level rather than the awkward mounting of an optic on top of the carrying handle of the standard A1 and A2 sights.

The Adoption of the M4 and M4A1 carbines

On August 15, 1994 the U.S. military adopted the M4 and M4A1 carbines. The only difference between the two is the M4 has a “burst” setting and the M4A1 has an “auto” setting. The vast majority of M4A1 carbines would be manufactured for the United States Special Operations Command (SOCOM).

The military specifications were drafted for the carbines including the inspections to be performed by Colt personnel as well as the on-site government inspector. The specifications state the endurance tests and allowable malfunctions per lot. The mil-specs have also written the processes of proof testing and magnetic particle inspecting of all barrels and bolts.

As of this writing, Colt has provided the U.S. military with an excess of 340,000 M4/M4A1 mil-spec carbines with tens-of-thousands more on order. This does not include foreign or law enforcement sales.

The Finalized M4 Carbine

The M4 carbine is a lightweight (5.9 pounds unloaded), gas operated, air cooled carbine capable of semi-automatic and burst fire (auto for the M4A1). Nearly 25% of the components of the M4 are not interchangeable with the M16A2, M16A3 and M16A4 rifles. With the telescopic stock fully extended, the carbine is 33 inches long and with the stock closed, 29.8 inches. The carbine uses the direct gas or gas impingement system utilizing an “exhaust pipe” that goes from the front sight assembly (where the gas port is located) back to the bolt carrier. The expansion chamber is located in the rear of the bolt carrier between the rear of the bolt and the front of the inside of the carrier. This creates a hammer-like blow that drives the carrier rearward unlocking the bolt, extracting and ejecting the fired cartridge case. The spring loaded buffer is compressed on its rearward motion and then drives the bolt carrier group forward stripping a cartridge off the top of the magazine, feeding, chambering and finally locking the bolt into the barrel extension. The benefit of this system is lightweight and accuracy. The barrel does not have some heavy piston attached to it preventing the natural barrel harmonics affecting accuracy. The drawback is that it directs fouling into the bolt carrier. This requires more frequent maintenance with extended use and is cleaned with normal cleaning solvent and brushes. Millions of rounds have been fired through the XM4 and M4 carbines in test conditions and this carbine is the preferred weapon by U.S. Forces.

Government Procurement

Once adopted by the military and the TDP finalized, the M4 went into production in 1994. Once in production, modifications or improvements would be extremely difficult for Colt to make. Any change would have to be authorized by Rock Island Arsenal and if the military in general were pleased with the performance they would not authorize any changes, particularly ones that add new parts to the inventory or create interchangeability problems with current weapons.

Popular belief is that the M4 carbine has not been improved by Colt since its adoption. Throughout the M4 design and procurement, Colt has proposed changes and updates for the M4 only to be overruled. An excellent example is the belated adoption of the “M4 Extractor Spring” which is identified by its gold color. Colt had redesigned the spring to give significant more strength, which is a major reliability enhancement in the carbines. Rather than adopt a new spring, which Colt was installing in all of their rifles and carbines except the one being delivered to the U.S. Department of Defense, the military put M231 Port Firing Weapon extractor springs in the M4s, just so as not to add a new part to the inventory. It was not until mid 2003 that this important reliability enhancement was authorized by Rock Island Arsenal and implemented into production. During the development phase of the XM4, Colt engineers proposed modifications to the bolt and barrel extension that would make the carbine handle better when being fired with water in the barrel. This idea was rejected by the government for reasons such as a violation of parts commonality and that they could not justify the cost/benefit of the change. They felt that the number of occasions that the weapon would be called upon to fire under such conditions was minute. Colt was overruled. Colt would not revisit this reliability enhancement until the development of their SCAR entries, which had “Over the Beach” requirement.

Without the direction or request from Colt’s customer, the U.S. Government, to make changes and improvement, Colt would not invest large amounts of resources into improvements if their largest customer would not accept them. Colt had proposed changes to the Army for a redesign of the bolt and related components to increase durability and reliability. Colt estimated the two year project would cost between one-half and two million dollars. Due to lack of funding as well as lack of government interest, the project never commenced.

There are two very different types of troops using the M4 family of carbines. The U.S. forces at large are very happy with the M4 carbine and prefer it to any other available weapon. The Special Operations Forces operators have been displeased but use them in a very different way from the rest. This situation makes it difficult for Colt to address SOCOM’s needs and make modifications. The M4, coming from an existing family of weapons, caused and still causes great difficulty to design the carbine to function to it’s potential with the requirements for interchangeability and the current attitude towards making changes within the government. On March 1, 2000, the Project Manager at Rock Island Arsenal stated, “The M4A1 carbine is already 3 times as reliable as called for in the specifications.”

SOCOM Taking the M4 to the limits and beyond.

As previously stated, the M4 was to be a lightweight carbine that was to be used by people who could not carry a rifle but needed more firepower than a pistol. However, once the M4A1 got into circulation within the special operations community the compactness, modularity, ease of operation and performance was immediately seen and they adopted the M4A1 as their main weapon. They would admittedly push the carbine well beyond its design intent.

SOCOM began reporting durability issues with their M4A1 carbines including blown barrels, broken bolts, failures to extract and over heating. None of which the regular Army units nor anyone else in the U.S. military were experiencing. Investigations immediately began by Rock Island Arsenal to determine if these problems were in fact problems with the design or manufacturing process of the carbine, or if the carbine was being used beyond its design intent. At this point, Colt was not able to make any changes to the firearm without this determination. The M4A1 is procured by the U.S. Army and subjected to the TDP. Any changes or improvements requests/requirements would have to be made by the U.S. Army, not SOCOM. This is the major difference between SOCOM employing a standard issue weapon versus them procuring their own weapon. By procuring their own weapon they are the customer and can make changes as they see fit. This is the case of the SCAR but not with the M4A1.

The first major investigation found the issue regarding blown barrels was clearly due to excessive operation beyond what the carbine was designed. The M4A1 was being used as a light machine gun or a SAW (Squad Automatic Weapon) laying down large amounts of cover fire. The barrels would reach their transformation temperature that is between 1,100 and 1,375 degrees. At these temperatures the barrel becomes soft and loses its heat-treating. Structural failure is just a matter of time. According to Rock Island’s testing, to get the barrel to this temperature you would have to fire 540 to 596 rounds within 3 to 3-1/2 minutes. The average infantry soldier does not carry this much ammunition as his combat load – the average being 210 rounds. This was clearly beyond the capabilities of a lightweight carbine and Rock Island Arsenal felt that this was not a deficiency in the design or manufacture of the weapon. Due to this type of use, Colt now provides all M4A1 carbines with a heavy barrel designed by Rock Island Arsenal and improved buffer to cope with this type of use. Recent interest has been given to the superiority of cold hammer forged barrels such as that used by H&K, IMI and Glock. The question has been asked, “Why does the M4 not have a hammer forged barrel?” The answer is very simple. Colt has offered them to the government and been rebuffed. Diemaco in Canada, now owned by Colt, has made them for the Canadian military since 1983.

Many SOCOM groups have problems with maintenance of the weapons, in particular replacing worn out components. One SEAL team said they did not keep track of malfunctions during missions to report back to an armorer to have the weapons fixed. Additionally, the training weapons that these operators use are the same ones they take into combat. The barrels and bolts have an unknown number of rounds through them. SOCOM operators fire an average of 24,000 rounds per year in training alone. Most all of the criticisms regarding this weapon system have come from a small element within the SOCOM community.

This weapon system has been in use with the British Special Forces for quite sometime. The SAS use the SFW (Special Forces Weapon) manufactured by Diemaco (now Colt Canada). These specialized carbines beat out Heckler & Koch G36 (identical operating mechanism to the HK416 and the XM8) and the SIG 500 series rifles and have seen action in both Afghanistan and Iraq. Unconfirmed reports say that the British Special Forces spent more money on the test and evaluation of these weapons than they did on the weapons they procured when the award was given to Diemaco. In addition, Diemaco (Colt Canada) has been asked to quote on weapons to replace the “perfected” L85A2.

The M4 is the preferred weapon for American forces overseas and the biggest problem they have with it is that there are simply not enough to go around. Clearly SOCOM needed their own weapon that would be suited for their requirements and that did not materialize until recently with the issuance of the SCAR developmental contract. Many people in the community speculate that the SCAR competition was conducted purely to keep the Program Executive Officer Soldier from forcing the XM8 on SOCOM.

Further Advancements at Colt

Colt has now split off into two companies. Colt Defense LLC is committed to military and law enforcement sales and Colt’s Manufacturing Company focus is the commercial market.

Colt Defense LLC is dedicated to providing military small arms throughout the world to the United States military and allies as they have done for nearly 170 years. Colt Defense has been diligently working on many military programs such as the SCAR program in which they submitted three entries. The SCAR (Special operations Combat Assault Rifle) program was, without a doubt, the most grueling firearms test ever conducted anywhere in the world. It was unwritten but clear that SOCOM wanted a piston driven mechanism. Colt developed a rifle with a piston mechanism as well as two direct gas rifles. The contract was awarded to FN Herstal of Belgium. Colt’s entries came in 2nd, 3rd and 4th. These are some of the most advanced military small arms in the world. Currently, Colt is working on a submission for the OICW and has plans to introduce a piston-operated Law Enforcement Carbine in early 2006.

In May of 2005, Colt purchased Diemaco from Heroux Devtek in Canada. Now called Colt Canada, Diemaco has been a supplier of parts to Colt for several years due to Diemaco manufactured mil-spec components from the Colt TDP. With the acquisition of Diemaco, Colt will take advantage of their excellent research and development team as well as their state of the art manufacturing facility.

Some sources would lead you to believe that the future of Colt and the M4 is on uncertain ground. The reality is, however; the U.S. government has recently placed a $55,000,000 order for M4s, to be delivered within 12 months, in addition to other large quantities of M4s for delivery in 2005 and 2006. With the U.S. military looking at a replacement weapon for the M16 and M4 family of weapons, their days could be numbered. However, if history has shown us anything in the last 40 years is that the military has tried to replace this family of weapons before. The ACR or Advanced Combat Rifle program of the mid 1980s for example. This was a trial of truly advanced weapons involving new types of ammunition including caseless, duplex and flechettes. The baseline rifle was the Colt M16A2. In the end, nothing achieved better combat performance than the baseline M16A2. The M16A2 has gone on to evolve into the M16A4 and the M4 carbine and, if given the opportunity, has much life left in it. This is why this family of weapons has been around for so many years because it evolved to the changing modern combat conditions. It would be far better for the U.S. military to improve the M4 and to keep the combat proven family of weapons than to invest in a new weapon that is not compatible with any of the current optics, mounts, magazines and SOPMOD components.

Now what of the future? The XM8 is not new or advanced but based off another Stoner designed weapon from the early 1960s; the AR18. Another unanswered question is why the government is spending money on a foreign weapon development without even the rights to the design. This was an issue that Colt dealt with during the Vietnam War. The decision was made in 1968 to sell/license the government the rights for the M16/M16A1 so if need be there could be other suppliers in case of a national emergency to procure needed small arms to equip our soldiers. Will there be enough of advancement in technology to justify the change to a new weapon? It hardly makes sense since the same ammunition is used so no difference in lethality or range. The U.S. military’s current weapon systems have been combat proven in every theater in the world. The M16/M4 families of weapons have long proven themselves the hard way: on the battlefield.

By Bob Campbell

Within the framework of the AR 15/M 16 rifle there are subtypes that are very interesting, perhaps even more useful than the original gun. One of the most popular, a weapon of almost legendary reputation, is the CAR 15/M 177 or M4 Carbine. The first short barrel short stock M 16 variants appeared in the late 1960’s. They met with varying degrees of success. I’ve fired most, a notable exception to my experience being the ‘port firing’ M 16’s designed for use within armored vehicles. Early guns in the CAR 15 series were sometimes called Commandos. The original guns coupled a ten inch barrel with a folding or collapsing stock. Colt had wished this line to be known as the CAR 15 line to signify the difference between Colt and Armalite production.

The short XM 177 received and kept the CAR 15 tag. These guns were criticized on several points, especially reliability. Col. Tony Herbert, the most decorated enlisted man of the Korean conflict served as a officer in Vietnam. He found the M 16 was a fine rifle, well suited to the conflict, but derided the CAR 15 as unreliable. He felt it had more show than performance, likening its image to that of the Thompson submachinegun of another war. The XM 177E2, with a longer 11.5 inch barrel and other types of ‘tweaking’, proved more reliable.

The XM 177E2 was dropped from production. The early short M 16’s were plagued with reliability and ammunition performance problems.

Later carbines were developed which featured 14.5 inch long barrels. These longer barrels work much better with the M 16 gas system and retain more of the 5.56mm cartridge’s effectiveness. This is a round that relies upon high velocity for effectiveness. Wound ballistics are compromised when the velocity falls below 2,500 fps. With enhanced ammunition performance and increased reliability, later variants such as the 1980’s M 16A2 carbine were much more effective weapons. Many in the Army wished to adopt the Carbine as a standard weapon but it remained for the most part a special team weapon, often issued to drivers and dog handlers or other needing a short light weapon. It is much more effective than any handgun or submachinegun, weapons often assigned this task.

The M4 and M4A1 are recent variants, being adopted in 1994. Both are in wide use by all of the services. Two models are in use. The M4 has the familiar ratchet-type three shot burst limiter. When the weapon is on full auto, it can be fired only in a three shot burst mode. At least in my hands, the usual result is two shots close together and one with greater dispersion. The M4A1 has the more conventional mode of fire.

A trained operator can tickle the trigger well enough to fire two to four round bursts in full auto mode. The trick is in training, a greater indicator of success in the field than gear. The M4’s currently in service are flat-top models, or M 16 variants with removable carrying handles. These weapons may easily be fitted with telescopic sights.

The M4 type weapon is also popular with civil agencies, especially Special Weapons and Tactics units. The needs of mobile SWAT teams are well served by the M4. The M4’s 14.5 inch barrel is not civilian legal, but a number of approximations are available with legal length 16 inch barrels. They mimic the M4 in a reasonable manner, of course without the full auto option. I’ve fired quite a few and they are accurate, reasonably compact weapons. Several versions are offered by Wilson Combat. Not as well known for his rifles, Wilson’s rifles and carbines are world class weapons.

The true M4 exhibits the following features—

• 14.5 inch, 1 in 7 inch twist barrel
• 7 3/4 inch round handguard
• Double heat shield
• Flat top receiver
• Four position buttstock—Closed/Full open/one half and three quarters open.

Early ammunition problems with the CAR 15 type guns are well documented. Often, downsizing a weapon does not work as well as the designer had hoped. M4’s currently in use feature an increased diameter gas port, which aids in overall function.

The M4 carbine has been well received in service, passing stringent testing. It is used by airborne units, SEALs, and other special operators.

Notably, the availability of the M4 carbine has resulted in less utilization of other weapons such as the Heckler and Koch MP5 and other weapons. The M4 can perform the same tasks but arguably much better, while fulfilling the mission envelope of the M16A2 as well.

The carbines are six inches shorter than the M16A2, a significant advantage when parachuting or traveling in a raft, and an advantage in house clearing as well.

The problems encountered by Israeli and Palestinian forces in house clearing with the M16 and Galil are well known. The UZI found favor with the Israelis. They would not allow Palestinian forces to use the UZI. The UZI is a good weapon of the type, but not comparable to the M4.

The question of accuracy and lethality remains with the M4. Accuracy to even 500 yards is comparable to but not equal to the M16A2. I have fired several short carbines at length. I chose Black Hills ammunition for the chore. Since their match grade loads are used by Marine sharpshooters, it felt appropriate. I used not only standard 55 grain loads but the 52 grain match load, the 60 grain softpoint, and a 68 grain match load. Results were very good. At 100 yards-and infantry engagement range is held to be one hundred to one hundred twenty five yards-accuracy was excellent.

The .223 cartridge must retain 2,500 fps or more of muzzle velocity to retain its lethality. With short submachinegun type barrels as seen on the CAR 15 this was not always possible, but it is a non issue with the M4.

The M4 provides an excellent alternative to the M16A2, with many good features and few tradeoffs. It is a fine weapon for the 21st century warrior.