Frankengun Challenge

By The Small Arms Review Editorial Staff

What is a “Frankengun”?

A “Frankengun” is just what it sounds like—a cross between Frankenstein’s Monster and a gun, in this case a machine gun. The phrase goes back to the early Internet days when legal machine gun owners would cross-pollinate weapon designs using parts, and sometimes movie voodoo type add-ons, to create something that fit their idea of a fun gun. Frankengun contests are held occasionally, and we at SAR like to encourage our readers to participate, making sure it’s legal as they do so. Much like our fabled “MacWaffle” contest (SAR Vol. 2, No. 4), where readers had to make a working waffle iron out of MAC flats, this is about having some fun.

We received several entries but chose the top 4 presented here. The winner of the Frankengun Challenge will be judged by the readers and receive a 3-year subscription to both SAR and SADJ. An RKI Certificate will be provided for those who put in an entry, which will be suitable for framing.

CONTESTANT 2: Richard Durham
M-11 A1 SWD COBRAY 380

The M-11 A1 SWD COBRAY 380 was converted to a 9mm by changing the barrel, reface bolt, weight and heavier spring. I used a Russian surplus 30-caliber MG barrel, chambered to a 30 Luger. It was cut down just like MAC barrels into the receiver, headspaced with an M1A bipod attachment. A slab of steel was used as a weight and as a charging handle—this added 5-ounce weight replaced the cocking knob. The long barrel upper in 30 Luger was cut from a Russian 7.62x54R machine gun barrel. The chamber end was cut off and machined to fit the upper. An M-14 bi-pod was fitted and a red dot scope added. The folding stock came from an VZ58 Rifle; the front sight, trigger guard and sight guard are all Uzi style. This weapon came new with a 9mm mag and grip. It didn’t work well for a 380 Machine Gun. Most of the time it would never feed correctly and jammed constantly, so that is why I converted it to a 9mm.

CONTESTANT 1: Ryan Radecki

This project came about in an effort to make the subgun experience more inviting. I like to shoot, but to me the best part is sharing the experience with family and friends and seeing their reactions. Some people are a little hesitant to try a subgun, but a tripod-mounted gun may be far less intimidating to some—and much safer, especially for first time shooters. I thought the MG-34 was a great candidate, but when I started looking, neither an FA Transferrable (15-20k) nor a semi-auto version (4-5k) appealed to me. I was fortunate that my subgun was an M-11/9, and I had come to appreciate its potential. I did a few estimates and mock ups. I drank a beer. I thought a MAC upper would fit inside that MG 34 receiver.

I was able to secure a really nice parts kit with a tripod, all in good shape. It included a dummy receiver—after lots of work with a local machine shop and gunsmith I was able to get the clearance machined out for the stock upper and mount it in place. I added a 16-inch barrel to the stock upper, with a steel extension inside the barrel jacket. Since the gun was going to be mag fed I used the feed tray for the charging handle integration. I could not find any good knurled handles for sale, so I used a pair of AR sight adjustment tools, welded into the bolt weight.
Special care was taken to ensure this remained an “upper” only in the legal sense—the bolt still recoils against the back of the NFA lower, which also contains the FCG and magwell which feeds it.

Stripping down this monster (knowing reassembly is inevitable) is no chore for the faint of heart. Clear it. Remove the charging handle and rear stock. Remove the blast cone (?) and unscrew the barrel until it can be pulled clear from the receiver. Unscrew the bolts holding the upper in place and remove the whole gun from the MG receiver, then remove the front receiver pin and strip it as you would any MAC.

Maintenance aside, the set-up is a blast to shoot in semi- and full-auto on the tripod or bipod. It’s surprisingly accurate, putting rounds on a rabbit-sized steel target at 30 yards. In full-auto it runs over 1,000 RPM with buffers in use—instead of individual marks on the steel, mag dumps produce lines where the stream of lead has stripped away the paint, each bullet impacting almost on top of the previous one. The added weight of the old 34 makes it easy to keep on target, and with a 16-inch barrel I have the option to put my VMAC receiver and bolt in it and use the M-11 to run another upper.

These uppers are safe to shoot—far more so than in their stock configurations. The FA lower used is legal/NFA registered.

CONTESTANT 3: Richard Hoffman

The Katsár Uzi was created for a number of reasons. My main reason for making it was to have a better subgun for use in subgun matches. I wanted an Uzi that would run a little faster than a full size Uzi but not as fast as the Mini Uzi. I liked the shorter front end of the Mini Uzi but like the cheek weld of the full size Uzi detachable stock. The final form gives you a very comfortable, very fast handling subgun. The second reason for creating the Katsár was from being asked to cut down registered full size Uzis into Mini Uzis. Because of the placement of the serial number on Uzis and not being able to move the serial number you wind up having to remove the rear strengthening ribs on the sides of the receiver and having plain flat sides on the back half. I do not think the finished product looks right, and I hate releasing work that I do not think is correct. It also gives a way to remove the blocking bar from a full size registered receiver without running afoul of ATF’s rules. I also came up with the idea for the Katsár from having semi-auto bolts for a Mini Uzi but no receivers or stocks and having receivers and stocks for a full size Uzi but no semi-auto bolts.

I started with a full size Uzi receiver, a Mini Uzi SMG trunnion and a Mini Uzi SMG open bolt. I cut two inches out of the receiver’s square section in front of the sear holes and behind where the sides of the receiver angles in to meet the trunnion. Next, I butted the two sections together and welded up the seam. I then had to mill off the rear bottom section of the rounded trunnion section of the receiver to make room for the front tong of the grip frame which then has a piece of sheet metal bent and welded into place to form the pocket for the tong of the grip frame. A new Mini Uzi front handguard lug needs to be machined and installed on the receiver and the hole for a Mini Uzi front sling swivel needs to be drilled. The final step to finishing the receiver is to install a Mini Uzi SMG trunnion and remove the semi-auto blocking bar if it was not previously done. On this particular Katsár I replaced the front sight base with a sight base for a Model “B”/Mini Uzi and machined the rear sight so I can use the better Model “B” sights on it. I then engraved the appropriate markings for the sights.

With the completion of the receiver it was now time to modify a full size Uzi top cover to fit the Katsár. This is relatively simple as you only need to remove a single section. I then welded the two pieces together and built up the joint with weld which I then shaped down to leave an appealing factory appearance. While I was at it I added one of my custom Burris FastFire red dot mounts so I can shoot the Katsár in Iron or optics classes.

The biggest problem was trying to find a spring with the proper dimensions so it would not fully compress and collapse the spring if the bolt fully recoiled. The spring had to be light enough to let the bolt cycle yet strong enough to make it feed and fire the round.

Once I had all that done it was time to test it. The initial test firing did not go as well as I was hoping it would. The spring was not strong enough. After trying different springs I finally found the right one. The rate of fire was absolutely perfect, but the lower and trigger group were being a little finicky. It would run fine for a few magazines then the sear would release and stop the bolt. It was also causing some erratic feed rates. I tried switching some parts around, and it never ran quite right. Once I replaced the grip frame the Katsár became exactly what I thought it would be. It is now as close to 100% reliable as I could ever get.

I was not happy with the efficiency of the compensator on the factory IMI Mini Uzi barrel. I took a cue from the current generation of pistol compensators used by the Action pistol builders and designed a compensator of my own. I machined a new barrel with a three port compensator machined right into the barrel. The new compensator works so well that it has virtually eliminated muzzle rise allowing you to stay on target even with the lighter front end and the faster rate of fire. The Katsár is so controllable I am not afraid to let just about anyone shoot it.

It was now time to make the whole thing look good. I started by grinding down and finishing all the welds. I welded up the model markings and re-engraved it Katsár Uzi. In Hebrew Katsár means “short.” So in English the model is “Short Uzi” which is exactly what it is. It is a short full size Uzi. I also engraved my company logo on the right rear side of the receiver. Once the engraving was finished and all the polishing was done, I media blasted all the metal parts and magnesium phosphate as called for on the original IMI Uzi blueprints. I then took it one step further by painting the outside of the Katsár in “Flat Dark Earth” with the small parts painted in “semi-gloss black” to give it some contrast. I also filled in the markings with “semi-gloss black” so they would stand out.

The finished Katsár Uzi is an extremely fast handling subgun. With the QD stock it wound up being about an inch shorter that the Mini Uzi. With the shorter and lighter Mini front end it transitions from one target to the next, faster than the full size, and it has less of a tendency to get caught up or knock into barricades and door frames during matches. Since the bolt is shorter and lighter than a full size Uzi SMG bolt it does not have as much of a lurch when firing the first round allowing you to place the first round more accurately which can be the difference between winning and losing a close match. With the increased length of travel over a Mini Uzi in the rear of the receiver the bolt does not slam into the rear of the receiver making the Katsár a much smoother running subgun than the Mini or full size Uzi. The increased rate of fire over a full size Uzi lets you move to the next target faster. Leaving the rear of the receiver the full size length allows you to use one of the quick detach wood or plastic stocks which gives you a very nice cheek weld allowing you to pick up the sight picture faster and more accurately. You can also bolt on a full size Uzi folding stock if that is your preference.

CONTESTANT 4: Eric Pate aka DistalRadius

First off, let me state that I am neither gunsmith nor machinist. I am just an NFA enthusiast with some basic garage tools, imagination and patience.

The base firearm is a fully transferrable SWD M11/9. This upper is built upon the discontinued Max-11DF slowfire upper by Lage Mfg. It feeds from converted 36rd Suomi magazines. The primary project goal was to make a stock that had the correct (for me) length of pull and drop which would allow a good sight picture with all aftermarket uppers. This has always been an issue due to the varying height of the sight planes on the OEM, Max-11 and Max-31 uppers. Secondary goals were the elimination of plastic components (excepting the buffer), the improvement of the ergonomics and overall aesthetics by introducing some curves into an otherwise blocky weapon.

The Handguard

The handguard is a set of Israeli FAL Heavy Barrel handguards mounted to a section of Browning 1919 barrel jacket. My suppressor outside diameter (YHM Wraith XL-QD) is 1.625 inches, and the internal diameter of the barrel jacket is about 1.71 inches, so it is a very close fit. The jacket is tapped and threaded to accept the four screws at the front end of the HG. The four screws at the rear of the HG were not used and are filled with dummy screw heads. The assembly is firmly attached to the upper receiver via the large pan-head screws.

The FAL HGs required some re-shaping to allow them to fit snug against the barrel jacket. They also needed to be relieved at the top to allow room for the Max’s upper receiver. I had to stain the HGs with dark walnut stain to get it to match the buttstock, this was then rubbed off slightly to give it the weathered look. A thin coat of matte polyurethane prevents any further wear. The cocking knob is a wooden FAL cocking knob. It was modified by plugging its cavity with a dowel, drilling it for the threaded shaft and then staining to match.

A quick note on the front sight, it is the KNS Precision crosshair with adjustable bead. An unusual choice for a subgun, but what about this build isn’t? I find that at close range (75 yards). Although quite difficult to sight-in on an open-bolt subgun, I’ve got the adjustable bead pretty close to where the bullet drops at 200 yards (IMI 158gr Subsonics).

The Grip

The grip is cut from a Thompson 1928 vertical grip with most of the material removed and the back cut to mimic an M11/9 grip panel. The heel mag release is shrouded by the grip and cannot be accessed normally. The thumb actuated mag release is a Lage unit with the internal steel linkage modified a bit to fit the different grip profile. Painted it black too, that always did bother me having that shiny piece of stainless on my gun.

The Stock

The stock was purchased secondhand as a Thompson Stock for M11/9 by Practical Solutions. I shortened it to 7.5 inches (from the back of the receiver) and re-profiled the buttplate to fit. I also had to create a new sling swivel pocket. I did this manually with a dremel (the horror!).

Functionally, this height works for me with all uppers. It is a high chin weld with the Max-11, a comfortable cheek weld with the Max-31, and I can still get a nice sight picture through the OEM upper if I pull my head down really tight. In each variation, my cheek is all the way forward on the rest. The OAL is right at 30 inches. The LOP is 14 inches from trigger to buttplate. For comparison, my AK underfolder measures 13 inches LOP, and my A2-stocked AR15 is 13.5 inches LOP!

The cheek piece is a modified Enfield #4 sniper cheek piece which was probably a waste of money since I re-shaped it so much I might as well have started with a blank!

Since I had a little extra space inside the trapdoor I took a very deep breath and drilled a pair of very deep holes just wide enough to house a pair of spare ejector rods. Having experienced the all-too-common frustration of over-enthusiastic newbies bending the ejector rod by jamming in an aftermarket magazine with no mag-stops, I swore I’d never again be without spares. This seemed a good way to ensure I’ve always got a couple with the gun. I think the sling is from a PPSh-41, a Knob Creek find.

This was a fun project, and I learned a lot in the process. The next incarnation will be even better as I am currently working on the Max-31 version which will interchangeably support a 6:00 Picatinny rail, the FAL HG panels or a Thompson vertical grip. I realize that the finished product is not for everyone, and a great many will find themselves asking “Why?” The answer lies in the finished combination of parts and how they turn a sheet metal box with notoriously poor ergonomics, performance and aesthetics into a smooth-shooting, eye-pleasing, built-for-comfort SMG.

UPDATE! And the winner is...

We are pleased to announce that SAR 2017 Frankengun Challenge Contestant #4, Eric Pate, has won a 3-year subscription for SAR and SADJ with his Distal Radius Max-11 Vintage, earning 44.4% of the votes. Contestants Richard Hoffman (33.3%), Ryan Radecki (18.5%), and Richard Durham (3.7%) have earned an RKI (Reasonably Knowledgeable Individual) Certificate for their notable entries!

Congratulations, Eric!

2018 Frankengun Challenge

Did you miss out on this challenge? Get designing your Frankengun for next year’s contest! The ‘vision’ needs to be safe to shoot and legal, but it can include improvements or be simply something that makes a futuristic fashion statement. The description of your Frankengun should be about 1200 words; describe your vision, what you started with, and what you did, and attach 4-5 high resolution photos. Entries due August 12, 2018 via email to lisa@chipotlepublishing.com.

This article first appeared in Small Arms Review V21N8 (October 2017)
and was posted online on August 18, 2017


Comments have not been generated for this article.