The MK Arms MK 760 Submachine Gun

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In April of 1966, a functionary in the U.S. Navy Department in Washington, DC, reached out to a sales representative for Smith & Wesson and floated the idea of designing and producing a 9mm submachine gun (SMG). SEALs, as well as other special units, were using the Swedish Carl Gustav m/45 during the Vietnam War. Troops in the field called this superb 9mm SMG the “Swedish K.” Sweden prided itself on its political neutrality and was none too pleased to be seeing its weapons used in combat in Vietnam. Realizing that the supply of new Swedish K’s and spare parts could dry up overnight, the Navy wanted a domestic replacement. That sales rep called back to the S&W headquarters and planted a seed.

There was a formal list of technical requirements from the Navy. The guns were needed urgently, they had to be both rugged and reliable, and the Navy stipulated select fire capability. Cost effectiveness was a consideration as was ease of maintenance. The magazine should hold 36 rounds, and the gun should cycle between 600 and 800 rounds per minute. With these marching orders, Dwayne Charron, the head of the M76 program for S&W, got busy. Before that time, he had never seen, held, or fired a Swedish K. With an active war driving the train, S&W made the M76 their top priority. From phone call to production examples was about nine months. The end result was everything the Navy had requested.

Technical Details

The S&W M76 was built around a heavy-gauge drawn steel tubular receiver. The inside of the tube was rifled like a gun barrel. These shallow helical flutes tended to clear debris away from the bolt and enhance reliability. The gun fired from the open bolt and featured a right-sided charging handle that reciprocated with the bolt.

The sights were welded in place, generously protected, and fixed. There was a perforated barrel shroud over the barrel—a spring-loaded detent kept it snug. The fire selector was a rotating bilateral level located in the middle of the fire control unit that was inconvenient to access no matter your handedness. The magazine release was a handy midline thumb lever.

The magazine used on the M76 was simply magnificent. A double-column, double-feed design, it was easily loaded with nothing fancier than a standard set of human fingers. Suomi and Swedish K 36-round magazines fit and function just fine in the M76, but only with modification to the back and front of the upper portion of the magazine.

If the M76 had a serious weakness, it was the side-folding stock. This appendage was formed from flat steel stock bent to shape and was fairly insubstantial. However, extending and collapsing was easy and intuitive, and it looked cool.

The Interloper

The Smith & Wesson M76 began production in 1967. However, draconian American red tape, and the associated onerous $200 transfer tax, kept most of these guns out of the hands of civilians. The Navy bought a few as did a handful of law enforcement agencies, but that market was inadequate to justify production costs. S&W wrapped up the project in 1974. However, by then, the SEALs had the weapons in inventory. They put out feelers for somebody who might be willing to supply spare parts.

In 1983, Mike Ruplinger and Kenneth Dominick launched a company called MK Arms. They secured the rights to the S&W M76 and began producing part-for-part copies they called the MK 760. The only difference between the MK 760 and the original was the pistol grip. That of the MK 760 was a solid aluminum casting that was arguably more robust than the plastic original.

The U.S. Navy purchased replacement parts for their M76’s. By the early 1980’s, inflation was starting to take some of the teeth out of the $200 transfer tax, so the American civilian market began waking up to machine gun ownership, so MK Arms offered their SMG for civilian sales. MK Arms also produced semi-auto closed-bolt versions: a pistol (although an extremely rare find) and a long-barreled carbine for unrestricted sales. Things looked fairly bright for MK Arms. Then, in 1986, Ronald Reagan signed the inaptly titled Firearms Owners Protection Act that outlawed the future manufacturing of machine guns for sale to civilians. However, MK Arms continued to make semi-auto carbines for a few years afterwards.

Clones and Knockoffs

MK Arms partner Kenneth Dominick started Global Arms and made a few guns he called the M76A1. Not much information is available regarding this venture. An Ohio company, JMB Distribution (JMBDistribution.com), produced a very similar weapon using unfinished registered tubes produced by a prolific 1980’s-era 
gunsmith named John Stemple. They called these guns the SW76. Stemple was a Class II manufacturer who registered about 2,000 tubes back before the 1986 ban.

The .45ACP version was called the Stemple 76/45. The 9mm SW76 sells for $9,400 apiece in the ad pages of Firearms News today. Believe it or not, that’s a bargain in the transferable machine gun world. The SW76 was almost but not quite identical to the originals. Stemple tubes sport a larger bore diameter to accommodate .45ACP entrails. The use of Stemple tubes meant the SW76 required a different bolt design and a sleeve to ensure smooth cycling. However, they run fine. Stemple tubes have been used to build all sorts of interesting guns like a Suomi-type SMG (it accepts 71-round drum magazines).

Firearms News Editor-in-Chief Vincent DeNiro gave his opinion on the history of another manufacturer he was involved with decades ago. In the year 2000, Todd Bailey, the owner of a company named Special Weapons, known for its cast-receiver HK94-type semi-auto carbine clones, heard from DeNiro (a distributor for Special Weapons at the time) that he/DeNiro and Ruplinger were negotiating the sale of the MK Arms’ tooling and entire parts inventory, which was stored in a two-car garage. Bailey flew out to Utah, where Ruplinger lived at the time, and purchased everything before DeNiro could finalize his offer.

Bailey then began manufacturing the “Omega-760” carbine via a sub-company he called “Omega Arms.” Where did the name come from? Well, DeNiro initially told Bailey about his idea to market the carbine around one of his favorite movies The Omega Man, which featured Charlton Heston wielding an S&W 76 SMG. The Omega 760 carbines were almost identical to the MK 760 carbines and utilized a lot of MK Arms’ old inventory of parts. The main difference was that the initial run used Sten magazines, later to be replaced with modified Suomi magazines. All of the grips for the entire production run were made of black plastic.

Despite the friction this caused with DeNiro, he stayed in contact with Bailey. Around 2003, “Omega Arms” built DeNiro a full-auto post-sample SW76 SMG and DeNiro also bought a semi-auto carbine (he still has the semi-auto). DeNiro stated, “The post-sample that Todd built me ran as well as the MK 760 SMG I bought back in 1988. The Special Weapons 76 serial number was 001.” After thousands of Omega 760 (aka SW 760) carbines were sold, production ceased—possibly due to the MK Arms parts running out and no desire to produce more. Currently, those carbines go for almost $2,000 today.

Trigger Time

The manual of arms for the MK 760 is easily mastered. Put the selector on safe, full auto, lock the bolt to the rear, insert a loaded magazine, point the gun at something you dislike, and squeeze. Note that the bolt will not retract in the safe position. The sights are almost worthless, but the iron sights on all handheld open-bolt automatic weapons are worthless in my opinion. My MK 760 cycles at around 750 rounds per minute and is eminently controllable.

The trigger on my gun is measured in short tons—like, legit, around 12 pounds. However, you get used to that soon enough. As the only manual safety is that hard-to-reach lever, having a heavy trigger isn’t necessarily a bad thing.

The factory magazine that came with my gun never ran well. In fact, I almost sold the thing many years ago after one particularly frustrating range session. Then I picked up half a dozen Suomi mags, and my MK 760 runs like a sewing machine. I never bothered to invest the mental capital to determine why the original mag was so finicky.

The Current Market

The MK 760 has long been considered an entry-level transferable machine gun. I bought mine from a Class III dealer in Montgomery, Alabama, back in 1994 for $800. He had this MK 760 and a Reising M50 for sale for the same price. I opted for the MK 760, because I had seen the gun in Omega Man. Ditto for DeNiro, and the one he bought in 1988 ran him $500.

Nowadays, all transferable guns are astronomically expensive. According to MachinegunPriceGuide.com, the going price for an original S&W M76 averages around $18,000 with a low of $13,000 and a high of $26,000. The MK 760 averages $14,000 with a low of $11,000 and a high of $15k. Stemple 76/45 prices run about the same. The MK 760 costs about what an M-10 (aka MAC-10) SMG does. However, thanks to its slower rate of fire and more elongated geometry, the MK 760 is the more shootable gun. Aftermarket kits will turn the “MAC” into all sorts of cool things. However, out of the box, the MK 760 offers more fun for the money. 

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