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Caliber - 9x19mm
Capacity - 32-round Zytel or 30-round steel mags
Action - Blowback; Open-Bolt Select-Fire
Barrel - 5 inches (short upper), 10 inches (long upper)
Weight - 4.26 lbs. (stock form)

Update

Background
The Cobray M-11/9 is the brainchild of Wayne Daniels, and is derived from the MAC-11 .380-caliber machine-pistol designed by Gordon Ingram in the late 1960s. Similar in design to the M-11, but with its receiver stretched to accommodate the 9x19mm round, the M-11/9 was produced by SWD, Inc. in the mid-1980s, until the 1986 ban on the manufacture of machine guns for civilian use. Many new-in-the-box M-11/9s were auctioned off when SWD filed for bankruptcy shortly thereafter. Through the 1990s, these guns were available from Class 3 dealers for just a few hundred dollars, and were generally looked down on by collectors and full-auto enthusiasts. The last few years have seen a cottage industry develop around modifications for the MAC family. This, coupled with the drying up of the last known stockpiles of new-in-box guns, has greatly fueled the M-11/9's popularity and has caused prices to skyrocket. Once regarded as "the Chevette of submachine guns," the M-11/9 is now thought an "undervalued investment" and "an ideal first SMG".

I bought this gun in late 2003, after going to the Glock List party in May and being totally spoiled by all of Todd's cool toys, then going shooting a couple months later with my brother and renting an UZI. The full-auto bug had bitten... HARD. I had originally wanted a full-size UZI, and Vector Arms was still selling them at a relatively reasonable price. But I procrastinated long enough that Vector's supply of pre-86 receivers ran out, and prices almost doubled virtually overnight. I could only watch helplessly as my dream UZI went from "expensive, but I can probably swing it" to "no way in hades". So I turned my thoughts toward the M-11/9, which was just about the only other "affordable" SMG available. With a vacuum left at the UZI's price point and signs that the MACs would soon be rushing up to fill it, I decided it was time to act. I contacted the same Class 3 dealer who had sold me my Outback suppressor, and it just so happened that a used M-11/9 had come in the day before. Without further hesitation, I put a down payment on it and started the purchase process rolling.

Fit & Finish
My M-11/9 was used but in pretty good shape. There was considerable wear on the upper receiver, but didn't bother me, as I planned to use the custom HK-sighted uppers I'd bought from AutoWerkes. The lower receiver, which is the serial-numbered and registered part (and thus is the ONLY part that's not replaceable), was in very good shape and had been refitted with an aftermarket paddle-style mag release. Wear on the bolt was minor, but I ordered a full set of replacement internals just the same.

Design
As it was originally conceived, the M-11/9 is not terribly impressive. It is lightweight (which exaggerates muzzle climb), lacks decent iron sights and a truly functional stock, cannot mount an optic, and feeds from an all-plastic magazine of questionable durability. Fortunately, there is an abundance of aftermarket uppers, stocks, grips, mags and barrel assemblies which can be added to make the M-11/9 into something much more usable. Some of these can be found on my M-11/9 Gear Page.

Slowfire Conversion
Even with the extra-heavy 10" CAR-OPT upper, a muzzle brake and the AR stock installed, shooting the unmodified M-11/9 is a challenge, simply because of its ~1200 RPM cyclic rate. Even veteran shooters with nimble fingers are unable to get off fewer than 3 rounds at a time using trigger control, and that's under ideal conditions (ie without the stress of competition). At the ISSMC match, 5-round bursts were the norm for me under pressure. The gun was controllable, but the high cyclic rate resulted in wasted ammunition on small targets like steel plates or poppers, which could be neutralized by 1-2 rounds. Additionally, the friction and impact forces generated by the bolt's high speeds produced a great deal of wear on the gun's internals, specifically where the bolt and sear interfaced. Too much wear in this area will cause a "runaway", where the gun continues to cycle in full-automatic even after the trigger is released until it runs out of ammunition. I speculated that slowing down the cyclic rate would not only improve the gun's controllability, but would also reduce the amount of ammunition expended and slow down the wear rate on the bolt and sear.

After talking to other MAC owners and looking at instructions and diagrams on the internet, I turned the gun over to a gunsmith friend of mine to have a TASK-style slowfire conversion done. This technique, pioneered by Jim Weaver and Monty Mendenhall of Team TASK, involves deactivating the MAC's own recoil spring and modifying the gun to utilize the recoil spring and buffer system from an AR-15. The actual conversion took some trial and error in getting everything to fit and function properly. First, the hole in the rear of the MAC bolt was tapped to accept an operating rod, which was fashioned from a 1/4"-20 steel bolt, and the back of the firing pin was relieved to clear the rod. Then, the rear of the receiver was drilled to allow the rod pass through and into the AR stock tube. After determining the necessary length for the op rod (so that it didn't bottom the buffer out in the tube when the bolt was retracted, and left a bit of pre-load on the buffer when the bolt was forward), we cut it to length and polished the striking end. Then we disabled the MAC's recoil spring by removing it from the rod and cutting it down so that it applied just enough tension to hold the backplate in place. Then we reassembled everything, tested for function and opened up the hole sizes until nothing was binding in the entire length of the bolt travel.

The conversion itself is only half the battle when it comes to taming the MAC; the type of AR buffer used is also of critical importance. Several users have resorted to fabricating custom buffers out of stainless steel or brass, or filling existing buffers with lead or tungsten in order to get a sufficiently heavy unit. Not wanting to mess with that, I went a different route and selected the CS MkII mechanical buffer from Advanced Armament. This is a heavy buffer with a midsection composed of free-floating tungsten weights. When the buffer bottoms out during the recoil stroke, these weights "are thrust to the rear, further compressing the buffer spring and providing a momentary delay in the forward travel of the bolt and buffer" (per the manual provided by AAC). However it works, this product really works. The cyclic rate of the slowfire-converted MAC falls somewhere between that of an Uzi and an MP5, in the 700-750 RPM range. The difference is like night and day; the slowfire gun is light-kicking and exceedingly smooth, and getting off double-taps or even singles just takes a bit of concentration and trigger-finger discipline – much less than shooting 3-round bursts in the unconverted gun. And most importantly, after some 500 rounds in slowfire mode, there is very little wear on the bolt and sear surfaces. Now this is a gun I wouldn't have any problem putting up against Uzis or MP5s in competition!

Summary
Overall, I am pleased with the M-11/9. This little gun is a total gas to shoot, and surprisingly accurate. And like my ARs, it's a versatile, modular platform. I can run it bone-stock as a bullet hose machine-pistol, or put on the CAR-OPT upper and AR stock and run it slowfire in Open Class competition, and in the future I'll be able to run the HRSC upper with a 3-lug mount and suppressor for some quiet full-auto fun in a compact package. I'm all about "bang for the buck" when it comes to Class 3 items, and the M-11/9 provides that in spades. Slowfire-converted and with an aftermarket upper and a good set of sights, it performs on par with the more reputable and much more expensive SMGs.

During a range session in August 2009, the gun abruptly stopped cycling, and the buffer and spring would not move inside the stock tube. Upon disassembly, I discovered that the AAC mechanical buffer had broken where the center stem is pinned to the head. Rather than buying another, I decided to experiment with a one-piece extra-heavy buffer from Hahn Precision. I hope that its longer length and 8-ounce weight will provide the necessary reliability and rate reduction, with superior durability to the AAC unit. I will post a review on the M-11/9 Gear Page once I have had a chance to evaluate it. Additionally, the gun has been suffering from "trip bounce," a common MAC malady where the sear trip causes the disconnector to be activated at the wrong time, producing single shots or bursts when the selector is set to full-auto. The expedient solution is to remove the trip entirely, rendering the gun capable of full-auto fire only. I have done this, but am pursuing possible fixes for the problem.