Freedom Machine Works SGMT Belt-Fed "Machine Gun"

The SGMT from Freedom Machine Works is an extraordinary semi-auto adaptation of the Combloc WWII belt-fed medium machinegun that replaced the M1910 Maxim in front line Soviet military service. Developed by master machinist John Earnest from an inspired semi-auto conversion originally crafted by Steve Sundin of Cincinnati, Ohio, the Freedom Machine Works semi-auto SGMT is a gun nerd’s dream. Poring over this thing will restore your faith in the supremacy of American engineering. The original SGMT was the tank coaxial version of the SGM which was itself an evolutionary development of the original SG43. The product of a desperate wartime design process, the SG action is novel, reliable, brilliant, and weird. For more than three quarters of a century, this weapon has soldiered on in war zones around the world. Now, thanks to some simply breathtaking work by John Earnest at Freedom Machine Works, the well-heeled gun geek who is really handy with tools can add a semi-auto rendition to his own stable.

Origin Story

The Soviets fought WWII with a variety of machineguns. The most common was the M1910 Maxim. The M1910 was an arctic-adapted version of the same basic weapon that claimed tens of thousands of lives in the blood-soaked trenches of the First World War. This water-cooled monster featured a big filler cap in the water jacket that could be charged with snow if needed, hence the term “Snow Cap Maxim.” However, all up on its wheeled mount, the M1910 Maxim weighed 138 pounds. Once the Russians weathered Stalingrad and began pushing back against the Nazi juggernaut, they needed something a bit more mobile. The answer was the SG-43. SG-43 is milspeak for Stankovyy pulyemyot sistyemy Goryunova. This means “Mounted Machinegun, Goryunov Design.” First introduced in 1943, the SG-43 was employed off of the M1910 Maxim wheeled mount, tripod mounts, and a variety of armored vehicles. It fired standard rimmed 7.62x54mm ammunition via a non-disintegrating belt. Despite a remarkably quirky design, it was a reliable and effective medium 
machinegun.

After WWII, the SG-43 was modified to become the SGM. SGM upgrades included sheet steel dust covers, a redesigned barrel lock mechanism, and a fluted barrel to assist in heat dissipation. The SGMT was essentially the same gun devoid of sights and fired via an electric solenoid for use in armored vehicles. These big guns were made under license in China, Czechoslovakia, and Poland. The Hungarians modified the design yet further into the KGK with a buttstock, pistol grip, and RPD bipod. The basic SGM design was produced through 1968 and has been used by all major Combloc-affiliated militaries. The SGM was commonly encountered by U.S. forces fighting in both Korea and Vietnam. In the late 1960’s, the role of the SGM was supplanted by the lighter and more advanced PKM belt-fed machinegun. The SGM can still be encountered in some of your less well-funded war zones even today.

Details

The SGM has a lot to accomplish in a fairly small space. The nature of Combloc non-disintegrating machinegun belts is such that the gun must extract the round backwards from the belt before shoving it forward for firing. Despite the obligate mechanical complexity implicit in that task, the SGM was an exceptionally reliable weapon. The most curious aspect of this uniformly curious gun is its method of locking. The weapon operates via a long-stroke gas-operated mechanism. However, where more conventional weapons lock via a rotating bolt, that of the SGM actually tilts sideways. That makes for some fairly bizarre geometry. Two claws extract the round from the belt, and a mechanical arm then pushes the cartridge forward for firing. The bolt rides atop a heavy bolt carrier and cams sideways into slots cut into the inside of the receiver to lock. The military gun fires from the open bolt and is full auto only. The heavy barrel is frankly huge. All that mass helps dissipate the heat of protracted firing. There is a built-in carrying handle to aid in barrel removal chores. The ample charging handle rides underneath the receiver and is readily accessible on the right. Curiously, the SGMT feeds from the right to the left.

Americanization

To transform a Soviet-era full-auto belt-fed machinegun into a legal semi-auto Title I firearm in the United States demands a fair amount of talent. The Americanized semi-auto version must operate from the closed bolt and utilize a separate striker. The details are elegant. John and Steve really outdid themselves with this thing. Steve thought it up, and John made it manufacturable. John cut his teeth as a machinist building parts for nuclear power generation systems. This guy knows his way around a machine shop. John doesn’t build guns to sell. You can’t just click on some website, lay down the plastic, and have a semi-auto SGMT show up at your local FFL. This is a DIY project for the guy with access to some decent machine tools and some proper talent. John designs and manufactures semi-auto solutions for builders. He doesn’t build customer guns in house. He does, however, sell the unique parts required along with instructions and drawings necessary to implement his system into a customer build.

To lock in battery, the bolt actually pivots to the right. Now, imagine that your task is to contrive a floating firing pin and separate striker that can work around that lateral movement to reliably allow the resurrected weapon to fire one shot with each squeeze of the trigger. The end result is mechanically inspired. The receiver of the SGM is slightly shorter than that of the wartime SG-43. As a result, there’s not enough room to include a separate striker mechanism. Some other designs incorporated a modified AR-15 fire control group unnaturally grafted onto the side of the receiver. John’s version, by contrast, adds a discrete fire control module onto the back of the receiver as part of the spade grip assembly. Where the previous sear mechanism engaged the bolt on the bottom, John’s is reversed to grab it on the top. The curiously angled geometry demanded of the laterally tilting bolt must be precise, but John and Steve pulled it off.

Communist labor was really cheap during the Cold War, so original Soviet versions of the SGM were each hand-fitted. As a result, many of the parts were not interchangeable between weapons. However, John’s version is graceful, inspired, and reliable. John builds his receivers up from thoroughly slagged originals. Along the way, he welds a four-inch tool steel restrictor bar in place that precludes the addition of a standard bolt carrier. The new semi-auto bolt carrier has a corresponding slot milled to accommodate this component. The hammer in the original design was a sizable steel tab that interfaced the bolt with the carrier. In the semi-auto version this piece is milled down to allow clearance for the firing pin. The new firing pin also incorporates a built-in spring to preclude slam fires. John and Steve moved the entire recoil spring assembly up front onto the gas piston to make room for the semi-auto parts. That was pretty cool.

How Does She Run?

The semi-auto SGMT is weirdly satisfying on the range. John explains that the butterfly trigger needs to be pressed with authority for optimal reliability. Teasing the trigger forward can potentially foment stoppages. However, running this gun aggressively and fast is kind of the point. I mounted the SGMT up on a period wheeled M1910 Maxim mount loaned to me by Liam Little at Mississippi Arms (MississippiArms.com). Liam’s shop is liberally festooned with belt-fed machineguns, and sundry black rifles blanket the walls. There is a Lahti 20mm anti-tank rifle and a tricked-out “Ma Deuce” fifty caliber arrayed on the floor. Mississippi Arms is the coolest gun shop I have ever seen. They sell both out of their storefront and online. The heavy steel wheeled carriage provides an exceptionally stable firing platform. As the tanker-version SGMT has no sights, the test gun John sent includes a Holosun red dot. The SGMT is more accurate than you might think considering the unnatural mechanical demands placed upon the design. However, nobody cares about that. This is serious ballistic eye candy, not a sniper rifle.

Getting One—Building One

John is essentially an inventor, not a firearms manufacturer. He will eventually be able to recommend a builder. For now, however, if you want one you’ll have to build it yourself. What John offers are the specific semi-auto parts required to resurrect a GI-surplus parts kit. John’s basic kit is $450 and includes the piston, piston end, recoil spring and spring spacer. The guide rod group consists of the guide rod, sear, sear spring, striker and striker spring. The trigger group includes the disconnector cradle, disconnector, disconnector return spring, and retainer along with the trigger link and link anchor. There is also a detailed instruction package with drawings, pictures, and procedures for installation, adjustment and maintenance. The customer is required to weld up their own receiver, install a denial bar, and modify the bolt and bolt carrier for semi auto. The details and drawings are all included in the instruction package. For an additional $100, John offers the SGMT fire control housing as an add-on option with the purchase of a standard SG43 build kit. This housing utilizes the original spade grips, thumb trigger, and safety bar from the solenoid fire control unit in your SGMT parts set (APEX Gun Parts is one source; APEXGunParts.com). This housing is pre-drilled to fit the thumb trigger and safety harvested from the original parts kit. The trigger group and transfer bar come pre-installed. All of John’s parts are black oxide coated and preassembled. The standard kit contains the additional parts required to build either an SG43 or KGKT parts kit up into a working semi-auto weapon. This project is not for the faint of heart. It takes some mad welding and machining skills to make this work. However, the end result is just incredibly cool. John’s example gun was Cerakoted by Black Boar Armory (BlackBoarCoatings.com) and looks factory new.

So, What’s the Point?

There is no imaginable practical utility to this gun. Don’t even try. Your skeptical gun-averse spouse will win that fight every single time. Then why would anybody in their right mind want one, particularly given how tough they are to build up from a demilled kit? The answer to that very reasonable question would be simply that the SGMT on its ample wheeled mount just looks so freaking cool. This rig would be right at home in a museum or guarding the palace of some flamboyant African warlord. When combined with the armored splinter shield and indestructible steel wheels, the overall effect is pretty darn impressive. It will instantly become the center of attention anyplace two or more gun nerds are gathered. The semi-auto SGMT really is exceptionally cool to shoot. What recoil there might be is readily absorbed by the mount, and the gun hits like a freight train downrange. The Holosun red dot means that the weapon is easy to lay on target.

With enough ammunition, this beast would readily shoot down trees or tear an old derelict car absolutely to pieces. Additionally, despite its prodigious all-up weight, the gun on its massive steel mount yet remains surprisingly portable. You may have scads of guns. However, I’d bet my reputation as a gun writer, such as it is, that you don’t have anything quite like this. The Freedom Machine Works SGMT is the hand-built bespoke range toy for the gun nerd of distinction. It costs a fortune, because it takes a zillion hours to design and build. However, the engineering is inspired and the execution sublime. You’ll need a decent vehicle to transport it to the range, and the Philistine giant Goliath was not man enough to fire this gun offhand. However, the weapon is as reliable as the tides and simply great fun. If you’re ready to take your gun world to the next level, this is the way to get there.

Freedom Machine Works SGMT Specs

• Type: Gas-operated belt-fed Semi-automatic
• Caliber: 7.62x54R
• Barrel: 28 in. 
• Overall Length: 45 in. 
• Weight: 30.4 lbs. (gun) / 90.4 lbs. (with mount) 
• Finish: Cerakote
• Sights: Holosun Red Dot
• MSRP: $450 plus parts set and gunsmithing services
• Contact: Freedom Machine Works

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