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MGA's Semiautomatic MK46 Variant
By Dan Shea
Photos provided by Machine Gun Armory LLC's Film & Video Unit

At the SAR East show, Long Mountain Outfitters debuted the first-ever Title-1 semi-automatic, belt-fed MK46. Having received ATF approval just hours before the show, this MK46-like semi-auto firearm is built to extremely high standards and is one of the finest quality “Black weapons” I have seen, which is in line with Machinegun Armory’s ethic to produce only the finest quality of parts, tools and/or weapons. Disclosure - if you don’t know it, this author is the General Manager of LMOLLC, and doesn’t usually write about products that LMO carries. In this case I made an exception; this is a very interesting and timely offering from MGA and you can buy directly from them as well as distributors like LMO .- Dan


The US Machine Gun Armory, LLC (MGA) is a Utah-based firm composed of engineers and machinists who provide reverse-engineering services to design and manufacture parts that the Military requires but can no longer find. Examples of this need, for instance, would be parts for aircraft currently in service today (e.g. The Fairchild A-10 Warthog) but whose parent company and/or parts suppliers are no longer present (Fairchild was bought in 2003).

The US Machine Gun Armory, of course, also produces parts, accessories and weaponry - some for civilians, some for LE/Military. And they also specialize in repairing and rebuilding (they offer a “reinforced” MK46, for instance, where the receiver is rebuilt to what MGA considers a strengthened model) Military M249s, MK46s, M240s. A few years ago they even made tools for these firearms.

Their newest creation is a civilian-legal, Title-1, ATF-approved (May 2009) belt-fed, semi-auto firearm similar in appearance to the FN designed and made MK46. The current model name for the MGA offering is the MGA MK46SA MOD 1, and it combines some of the features of the FN M249 family of guns as well as the H&K closed bolt, hammer operated method of operation, making the gun rather unique and the only semi-auto MK46-like gun the author has ever seen. There have been some very nicely made M249 type semi-autos on the market, but never a MK46 semi-auto.

The author was present when in 2006, having just completed the LMO military level M249 and M240 Armorer’s Courses, two of the MGA engineers/gunsmiths, always fond of the Minimi, M249 and M240 style of guns, decided then and there to build a semi-auto MK46. Much discussion followed on how to design a proper semi-automatic system that would be reliable and robust, as well as user-friendly.

Subsequent to examining numerous firearms in the LMO Working Reference Collection, and discussing some ideas for the basic operation, the MGA team virtually disappeared for almost two years only to resurface in late 2008 when they sent LMO a prototype for review. At that point the proof of concept was finished, and the MGA MK46SA was impressive and unique but as a prototype there were still a few rough edges.

After making very few changes, they sent the prototype weapon, model MGA MK46 MOD 0, along with a full-auto military type MK46 (a Post-86 dealer sample) to the ATF Tech Branch in April 2009 for evaluation and approval. Being well thought out and designed with adherence to both high-quality design and manufacturing standards, as well as keeping in mind all the legal issues, they quickly received approval on their first submission without being asked for any changes or modifications. They had done their homework on what the characteristics would need to be in order to make the MK46SA not only reliable, but legally correct so that it was not readily convertible to fully automatic. Getting the approval immediately was a feather in their cap denoting diligence and attention to detail.

During the summer of 2009, though no flaws were found, MGA upgraded the prototype in small ways (such as including a bolt hold-open) and upgraded the current model name to the MOD 1 moniker in order to differentiate the newest gun from the early models.

In the fall of 2009, the US Machine Gun Armory, in response to sheriffs and police department inquiries, produced a burst-pack version of the gun for law enforcement and military agencies. Eric Cline, MGA’s CEO states, “We are not in any way trying to compete with FN’s product. Our products fit a niche that is unique and can’t be achieved with the military MK46. Many law enforcement agencies have told us that having a semiautomatic or burst-pack version of a MK46 would be more useful, desirable and palatable to their legal sections than a full-auto military weapon. These departments were not buying the military models for that reason, and here was a niche that MGA could fill.” Eric went on to say that some agencies do want a full-auto gun so they can provide that option, but the closed bolt, hammer-operated, HK-sear design for the LE/Military model is meant for domestic security and not military operations.

Though completely different in all key ways, the gun itself looks almost identical to the US MK46. Only by looking closely does one notice that the area just above the trigger on the MGA gun is about one-half inch taller and half an inch longer than that of its military cousin.

Design Details

In 2006, when MGA set out to build a high-quality, custom made, semi-auto MK46-type of SAW for the civilian market, the first thing the Machine Gun Armory engineering staff did was acquire an old Minimi, and study that gun in great detail.

They then used state-of-the-art scanning tools to reverse engineer that 1970s era firearm which resulted in a series of highly detailed CAD models for virtually every part.

They then used those designs to replicate from scratch (and register it with the ATF) an exact copy of that Minimi-style full-auto Post Sample gun. They then updated their Minimi-style CAD models to that of the more modern military MK46 and manufactured an exact copy of the MK46 from scratch (and again registering it as a Post Sample with the ATF). This was done, Cline said, in order to understand how to make the exterior accessories look similar to the Military weapon and to help them refine their military weapon repairing and rebuilding services. Not only do they repair MK46s and M249s, but they offer a “Reinforced MK46” which takes down a military MK46 and then rebuilds it back up with new parts, strengthened welds, and what MGA claims are stronger receiver components (for instance, they use a Wire EDM to create the buttstock mounts instead of a bended sheet metal process).

MGA also offers a service to convert PreMay Dealer Sample Minimis and M-249s to MK46 configuration.

After replicating an exact copy of the MK46 they then worked on their design to convert the open-bolt firing, full-auto design of the Minimi/M249/MK46 to a uniquely different receiver with a closed-bolt, floating firing pin, hammer-fired design utilizing a Heckler & Koch trigger group including a semi-auto disconnect.

They then modified the receiver as well and the trigger housing for the semi-auto MGA MK46SA is not interchangeable in any way with the FN military gun. In fact, MGA points out that most MK46 accessories will fit their semi-auto gun - but the operating groups are totally different and FN MK46 bolts, bolt carriers, etc., will not fit the MGA gun. This is not a true MK46, it is a newly designed operating group that uses the reliable HK fire control group with modified hammer.

Of course, utilizing a standard HK semi-auto trigger pack and custom made hammer also required the extensive re-design of the operating group including the bolt, bolt carrier, firing pin, and the use of a forward positioned “trapped recoil spring” instead of the rear-positioned recoil spring and buffer system found on the military weapon. Manufacturing

The MGA guns are custom made and hand crafted, built to tolerances much tighter than Mil-Spec. MGA machinists and gunsmiths check and adjust tolerances of every moving part to insure that all work correctly. These firearms are all custom made on a quality production line. Every receiver that has been built goes through a reheating and straightening step, often more than once, to make them function reliably. Though the gun carries a hefty price tag, the quality reflects the attention to detail and expert hand-craftsmanship.

Title One Semi-Automatic MGA MK46SA Mod 1

The semi-automatic MGA MK46SA Mod 1 was approved by the ATF in May of 2009. The gun comes with a 1 year warranty, user manual, and can be purchased with numerous optional accessories. MGA is running one production run of only 30 semiautomatic guns, making this a rare collector’s item right from the start.

Full-Auto MGA MK46LE Mod 1 (LE/Mil ONLY)

MGA also makes this firearm in a full-auto version for law enforcement and military clients interested in an alternative to the military type full auto only. Since they utilize an H&K select fire control system they offer the gun with a burst pack option. Hence, the MGA MK46LE is the only burst pack capable MK46 available today.

Live Firing the MGA MK46 Semi-Auto and Full-Auto Guns

The MK46SA is aesthetically pleasing, built extremely well and appears to be of the highest quality. But would it fire? Would it hold up under extreme use?

Over the past few months, multiple shoots were done with the MGA MK46SA MOD 1 semi-auto, the MGA MK46LE MOD 1 SEF and 3-round burst pack model.

Because the H&K semiautomatic trigger group MGA uses in their guns requires more vertical space around the trigger, the MK46-style handgrip is half of an inch lower than that of the military SAWs (Minimi, M249, MK46). The lower grip actually makes for a nice ergonomic feel, allowing a very different control feel from the military MK46.

The rate of fire in the LE model appeared to be the same as the military MK46 and one of the MGA guns did a 4,000 round semi-continuous fire, in order to see if anything would break. The only problem noted was that the non-hardened hammer they used showed dimples from striking the back of the hardened firing pin. MGA knew about this and all new MK46SA come with the new hardened hammer.

Videos showing the operation of the semi-auto and the law enforcement burst-pack and SEF versions of the MGA guns can be found on their website:

The Future

Machinegun Armory is planning to build its 6.8mm SPC burst-pack capable belt-fed machine gun next.

The company hopes to get police departments and Homeland Security agencies in need of greater fire power, but not necessarily wanting a fully automatic belt fed, to adopt its burst-pack belt-fed machine guns. MGA is also seriously considering building a semi-auto MK48 type weapon and other calibers, using their unique operating system.


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