Text & Photos by Jeff W. Zimba
Since the mid 1960s, the Minigun has been much more of a star on the battlefield as it has on the silver screen. With its distinct sound and enormous rate of fire, it is immediately distinguishable by all within even a remote proximity. It has been over 40 years since the lore of “Puff the Magic Dragon” began, and with modern technology assisting in fine-tuning this incredible weapon system even more, it appears that it is here for many more years to come.
Capable of firing in excess of 6,000 rounds per minute and designed after the M61A1 20mm Vulcan, the Minigun can inflict a devastating amount of damage in a minimal amount of time. With several rate of fire settings depending upon the model and manufacturer, there is no question that firing up to 100 rounds of 7.62x51mm NATO (.308 Win) per SECOND, for several seconds, has the potential to eliminate whatever immediate threat is being targeted. While some believe that more is better, the engineers at Garwood Industries have other ideas.
Garwood Industries of Scottsdale Arizona is a certified government contractor specializing in the design and manufacture of Miniguns. They have been studying the Minigun design for some time and have developed their latest project, the M-134G, which incorporates several upgrades to the original G.E. system designed over 40 years ago. Through their extensive research they have discovered that the highest rate of fire the system is possible of operating at may not be the optimum rate of fire for hit potential. After several extended firing exercises, Garwood collected enough data to conclude that the optimum rate of fire for the Minigun system is approximately 3,200 rounds per minute (rpm). This cyclic rate provides the operator with the maximum amount of target saturation while expending a minimum amount of ammunition. Even a novice gunner can achieve a greater rate of accuracy at the 3,200 rpm mark. Because of these findings the M-134G is being produced and offered with this firing rate as well as 4,000 rpm and the previous standard of 3,000 rpm.
While the rate of fire research and adjustments have been quite significant, several other upgrades and improvements have been implemented by Garwood Industries, and for the first time since General Electric manufactured Miniguns in the 1960s, the complete M-134G system is being manufactured to meet and exceed military requirements. To accomplish this, all of the weapons components adhere to ISO standards to ensure quality traceability.
A Brief Tour Inside The Minigun
The differences in the M134G are numerous and maybe even slightly confusing unless you are intimately familiar with the method on which the system functions. Everyone knows the barrels spin and it shoots fast but beyond that, the details start to depart from traditional firearms mechanisms quite fast. In order to learn about the system upgrades, let’s first look at how the system actually functions. (For a very detailed look inside the Minigun and how it works, see Small Arms Review Vol. 5, No. 7, April, 2002)
First, it is important to know that the system is operated from an outside power source and not dependant upon ammunition ignition or produced recoil of any kind to function. In the case of the M-134G this power is supplied by an improved 28 Volt DC motor.
In the most simplistic terms, the Minigun is a single group of 6 complete guns working in unison as a single gun. This takes place inside a single “receiver.” In the M-134 system there are 6 barrels and 6 complete bolts and bolt carriers, each containing a firing pin and spring. Each bolt also has a cam bearing which guides it along a cam path inside the receiver.
To follow a single round through the entire mechanism it would take this route: Linked with several other rounds, life starts in an ammo box and proceeds through a feed chute into the feeder/delinker. As the main drive (powered) gear rotates, it spins the entire rotor mechanism turning a parallel gear to the rear of the rotor. This gear engages the feeder/delinker gear and pulls the linked ammo up the feed chute and into the gun. As the feeder/delinker rotates, a set of cam bearings (similar to those on the bolts) and attached to feeder push rods, follow another spiral cam path and progressively push the rounds out of the links at the prescribed time in the rotation. The stripped rounds are pushed into the feeder wheel and continue to rotate until meeting the counter-rotating rotor mechanism and fed into a corresponding bolt face with the assistance of the guide bar, or “hand-off” as it is sometimes referred to. The round travels in the bolt (which is following its own cam path via the bolt cam bearing) until reaching the correct position where the bolt is locked and the round is fired. As the rotor continues to rotate, the bolt is unlocked after firing and the fired case travels to the ejection position where it is assisted in ejection by the guide bar.
Other parts that may be referred to when discussing the function of the Minigun include the clutch assembly, the booster assembly and the safing sector. The clutch assembly is utilized in conjunction with the feeder/delinker. The function of the clutch is to almost immediately stop the gun from firing when the fire button is released without dumping live rounds into the expended brass pile. This is accomplished by stopping the feeder/delinker functions and booster assembly simultaneously.
The booster assembly is the mechanism that assists in feeding the Minigun. In belt pulls of over 8 feet in height and greater, a stretching or stressing of the links can occur from the weight of the belt, combined with the speed in which it is being pulled. If this happens the belt can break or the stretched links can create a jam. In essence, the booster pushes the ammo up from the source and works to lighten the load on the feeder/delinker. The belt “push” rate of the booster assembly must be timed exactly the same as the belt “pull” rate of the feeder/delinker to avoid other feeding problems such as jamming, binding and belt breakage.
The safing sector is essentially an access door which when opened, interrupts the bolt cam path in the receiver, and prevents the gun from being fired. When open it also allows the removal of the bolts.
The Garwood Upgrades
Now that we have a basic understanding of the operation of the gun and its components, we can get a little deeper into the improvements offered with the M-134G.
• The Drive Motor – Many positive improvements to the tried and true General Electric drive motor have been implemented using products not previously available. These improvements allow the motor to be lighter and extend the service life at the same time. Since the beginning of the M-134G project, three proactive upgrades have been accomplished and even the solenoid has been revised several times.
• Fire Control Unit – Garwood Industries has upgraded the fire control unit using state-of-the-art electronics to guarantee unsurpassed reliability not previously thought possible. A manual override for the booster assembly is standard on all M-134G models.
• Feeder/Delinker – The Garwood feeder/delinker has an upgraded cartridge handoff system and has been finished with a new high-performance coating that will increase longevity and enhance operation in all environments.
• The Barrel Cluster Assembly – The barrel cluster assembly has been re-engineered to both lighten the weapon system and improve performance. The newly designed flash suppressor completely eliminates the blinding flash that was a constant problem with older Minigun systems. New designs are being tested to even inhibit the sparks that are created from unburned powder and it is expected to completely eliminate the visual signature under fire.
• The Bolts – A new government model is being finalized that utilizes a new proprietary bolt design. The material and coatings used in this latest system greatly improve the longevity of the system and exceed current specifications.
• Grip Assembly – The M-134G spade grip assembly is integral with the receiver through a new proprietary mounting lug. Previous versions only mounted to the clutch or other components. The new mounting area greatly improves the rigidity of the system.
• Rail System – The M-134G incorporates a rail system that allows the easy mounting of several accessories that may be found useful to its operator. These include, but are not limited to, scopes, electronic sights, lasers and spot lights.
Torture Testing & Range Time
Some ideas look great on paper and even make sense under controlled environments, but don’t necessarily make the grade in real world situations. Because of this, torture testing is an important part of the Research & Developmental phase for proving any new weapon system. Shooting massive quantities of ammo is a very legitimate and serious part of the gun industry to determine what, when and if parts fail.
In 2006, Garwood Industries fired over one-half-million rounds during the torture testing phase of one of the earliest guns. During the entire series of tests there were zero recorded failures of any major components. Throughout the whole test cycle only minor pins and springs required occasional replacement, much to the satisfaction of all principals and engineers involved.
The time spent live-fire testing the Garwood M-134G Minigun was as educational and interesting as it was enjoyable. This writer was accompanied to the range by two of Garwood’s major principals, Tracy Garwood and Randy Myers. Tracy and Randy are both extremely passionate about their product and both are a wealth of information pertaining not only to their particular system, but with the entire history and development of the Minigun since its inception. Both are enthusiastic and happy to share their knowledge with anyone who is interested in educating themselves about it.
Range time was spent in the Nevada desert and since we were so close to Las Vegas, we were provided with an original military H1 Humvee for use as a rolling mount by Long Mountain Outfitters, LLC. We were also allowed access to their classroom facilities to disassemble the M-134G and take the studio photographs that accompany this article.
The live fire exercises went off without a hitch. The operating speed during testing was in the 4,000 rpm range and the ring mount contained every bit of the 375 pounds of peak thrust from the recoil, and allowed the shooter to focus on shot placement. A bright laser was used as an aiming device, and the hail of lead to follow the green dot in the impact area was a testimonial to the effectiveness of the system. The only glitch we encountered was when we were shooting without the assistance of a booster assembly and we got a bit overzealous with the hanging length of our belts. A broken link was quickly removed and we were back under way.
This writer has had the opportunity to fire several Minigun systems and it remains a thrilling experience every time. As exciting as it is, having the opportunity to get inside and really digest how the new upgrades work in conjunction with one another was equally as stimulating. The Minigun is a weapon system unlike any other, and the opportunity to intimately study and build a better understanding of it is not taken lightly or without appreciation. In every conversation with Tracy and Randy about this project over the last few years always brings a newly found excitement and enthusiasm as more upgrades are discovered or new test results are recorded.
After talking at length about manufacturing and production capabilities, most of my questions about current or future military use were answered without having to ask them. While we were going over some of the technical specifications of the system, Tracy received a private phone call that had him smiling from ear to ear. He had to excuse himself for a few minutes to wrap up an order for a 40 gun Helicopter Gunship deal they had been approached about earlier. It looks like the Garwood M-134G is going to be around for a while.
Garwood Industries P.O. Box 15393
Scottsdale, AZ 85267
Phone: (800) 464-1892
|This article first appeared in Small Arms Review V11N1 (October 2007)|
and was posted online on November 1, 2011