My initial test-fire of the M-11/9 was conducted with the HRSC upper installed. Fit with the lower receiver was snug, but the HRSC upper installed without incident. The side-cocker is a welcome improvement over the standard top-cocking design; not only does it free up the top of the receiver for an optics rail, but the handle itself does not reciprocate with the bolt. This eliminates stress fractures in the cocking handle, which can cause it to snap off in mid-cycle and come flying back at the shooter's face - a commonplace problem with stock MACs. HK sights were well-regulated at about 30 feet, and required no adjustments. I found I prefer the large #2 aperture for most full-auto applications; the open notch is too open, and the smaller #3 and #4 apertures are too small to allow fast acquisition and unobstructed target view at close ranges (but might do well for semi-auto fire on farther targets). In short, the HRSC upper is expertly conceived and well-built, and is an easy way to vastly improve the functionality of the M-11/9.
AutoWerkes CAR-OPT Upper
The CAR-OPT is essentially a stretched version of the HRSC upper. Like the HRSC, it is built on an MPA side-cocking receiver, and features AW's hi-rise HK sighting system. The front end is built around a 10" carbine barrel enclosed in a Cobray barrel shroud. The shroud is vented for heat dissipation, and incorporates a vertical foregrip on the bottom. Along the top of the shroud is attached an elongated riser, bearing the HK front sight. The end result is a clean, uniform appearance; the riser, optics rail and HK sights all flow together into a virtually continuous assembly. As with the HRSC upper, I special-ordered the muzzle threaded to 1/2x28, and the front sight hood cut to allow a less cluttered sight picture with optics.
Shooting the CAR-OPT upper is pure joy! The added mass of the longer barrel and shroud increases overall weight and puts the balance point well forward, but this translates directly into less recoil and more controllability on full-auto. The accuracy boost from the longer sight radius and 10" barrel is noticeable, as well. Though a longer barrel will increase a gun's full-auto cyclic rate, when you're already beating the heck out of 1200 RPM, the increase isn't going to be noticeable. The vertical foregrip is comfortable and rigid, and provides additional leverage to keep the muzzle down during long bursts. In this configuration, the M-11/9 compares favorably to a full-size UZI with a kicked-up rate of fire. The CAR-OPT has quickly become my favorite of the two AutoWerkes uppers, especially when wearing the SPOT MkIII red-dot sight.
AutoWerkes Vertical Grip
The K2 vertical grip (pictured here with the HRSC upper) attaches at the base of the M-11/9's barrel, and provides a forward point of control far superior to the stock "strap hanger" and most other aftermarket vertical grip designs. The mount and grip are machined from aluminum and wear the same parkerized finish as the AW uppers. Installation is a breeze; the grip locks down with a single cross-bolt and is VERY solid, with no tendency to wiggle or rotate during use. Additionally, the low-profile mount leaves the coarse threads at the base of the barrel exposed, allowing use of a Sionics or Bowers-style suppressor, or a barrel extension. The round cross-section of the grip itself is hand-filling and quite comfortable, and the built-in hand stop is a nice safety feature. The hand stop also has a hole on the left side, for attaching an HK-style snap hook sling.
The first time out with the K2, the bolt holding the grip and hand stop to the clamp assembly loosened, allowing the grip to rotate around its axis. I put a bit of Loctite on the threads and torqued the bolt down again, and that seemed to fix the problem. The clamp itself has not loosened in the several hundred rounds fired since its installation. Ergonomics of the grip are quite good, although shooters with large hands may find it somewhat short (like the MP5-K grip after which it was modeled).
AutoWerkes RRD-2 Rate Reducer
The RRD-2 consists of a sheet metal body with stabilizing tabs and a spring-loaded arm (actually a modified M-16 hammer), and is designed to fit into the MAC lower receiver behind the magazine well with no alterations to the weapon. The spring-loaded arm places additonal drag on the bolt as it travels rearward, thus reducing the gun's cyclic rate.
I installed the RRD-2 per the illustrated instruction sheet, making sure to dry-cycle the gun several times with the RRD-2 in place. Initially the gun would not even re-cock for the second shot, so I removed the RRD-2, lubricated the arm and flexed it repeatedly before reinstalling. Subsequent runs showed better functioning, and the cyclic rate was definitely reduced - it was possible to get off single shots in full-auto mode, which is nearly impossible with the stock gun except for shooters with exceptionally disciplined trigger fingers! However, the trade-off came in the form of a delayed trigger response, which would sometimes result in an additonal shot or two at the end of a burst after letting off the trigger! Erik at AutoWerkes advised that the RRD-2 may take a couple hundred rounds to break in and begin operating reliably, but this was such a serious safety issue that I did not feel comfortable giving it the chance to do so. With less than 100 rounds fired, I sold the RRD-2 for exactly what I had paid for it. I have decided to pursue a TASK-style slowfire conversion instead, which is a more involved but ultimately better solution to the rate reduction issue, IMHO (more on this later). It is to be noted that I have not gotten any complaints from the buyer of the RRD-2, so maybe a little break-in was all it needed to get running properly. I hope that is the case!
AR Stock Adapters
One of the most useful upgrades for the M-11/9 is replacing the wireform stock with something more solid that offers better durability and cheek weld. There are many replacement stocks on the market, from the fixed Cobray carbine stock to Uzi-, AK- and MP5-style side folders, to the Assault and Tactical stocks available from AutoWerkes. One of the most verstatile options is the AR stock adapter, which allows you to mount any AR-15 stock assembly. Possibilities include the A1, A2, 4-position CAR, 6-position M4, VLTOR, MagPul CTR, ACE skeletonized, Boom Tube, SOCOM adjustable and others. Several manufacturers offer AR stock adapters; I evaluated those from AutoWerkes and Tactical Innovations (both of which are out of production as of 2009).
The Tactical Innovations adapter, designed by Craig Wheatley, consists of two pieces held together by hex screws. Is very well constructed and finished, but is a bit heavy and verges on over-engineered. It installs into the back of the gun in the same manner as the wire stock, and is held in place by a locking bar and hex bolt that replace the standard stock latching equipment. The vertical body of the adapter is tall, and features a roughly oval cutout that should mate with the detent on the CAR stock locking plate (but did not, with my RRA 6-position stock). The threaded portion of the adapter is an open ring, and is sufficiently deep to allow the buffer tube several turns before it hits the rear of the receiver, providing a secure mount. My problem with the Tactical Innovations adapter is that it was intended for use with optics, and places the stock (and the shooter's eye) far too high to access the gun's iron sights (even the hi-rise HK type). No mention of this incompatibility is made on the TI web site, nor in any documentation accompanying the adapter.
The AutoWerkes adapter is lighter and smaller than the TI product, and is welded rather than bolted together.
It installs in the same manner as the TI adapter, but can either be secured with the bottom bolt, or used with the
factory stock latching mechanism for a quick-detach feature. The threaded portion of the adapter is a shallow ring
with a closed back. This allows the buffer tube fewer turns when mounting, but the attachment does not seem any
less secure. The backplate is drilled to accommodate the operating rod used in the TASK-style "slow-fire" conversions.
The main advantage of the AutoWerkes adapter is that it positions the stock much lower, and is designed specifically
to allow use of AW's raised HK iron sights. Because of this lower positioning, the adapter cannot engage the detent
on the CAR stock locking plate; the buffer tube needs to be secured using only the castle nut and Loctite, and can
potentially move or rotate if sufficient pressure is applied.
Recon Ordnance Steel Magazines
One of the weakest links in the M-11/9 system is the factory Zytel magazine. These mags are constructed entirely of polymer, as opposed to metal-reinforced polymer like Glock mags. Under the rapid cycling of the bolt and the heat of full-auto fire, the feed lips tend to wear rather quickly, causing various types of malfunctions. There are also reports of the seams splitting, and other structural failures. Enter Jerry Prasser of Recon Ordnance, who offers what is arguably the best magazine available for the M-11/9. These double-stack/single-feed mags are constructed of heavy-gauge steel with welded seams and a parkerized finish. They start life as magazines for the Argentine PAM-2 9mm subgun, then are professionally converted by Jerry to fit the M-11/9. These mags fit in the M-11/9 magwell with no rattle or binding, lock up tight and release cleanly. Feed reliability is excellent for a single-feed design, though the feed lips may require some minor fitting or reshaping to work reliably in some guns. Of the 12 magazines I initially bought, I had a four "problem children" that would not run 100%. Instead of sending them back to Jerry for replacement, I sent them off to Mike Sessa (known on the gun boards as "Bust Off" and had them cut down and rewelded into two extra-long 55-round "X-Mags" for competition use. They work.
A couple other notes: 1) Because the Recon mags are thicker than the Zytel, they will not lock into the magwell with the wireform stock in the retracted position. No biggie, since you'll probably want to replace that stock with something better, anyway... or just deploy the stock before you insert the mag. 2) With the Recon mag loaded to full capacity (30), it will not lock into the magwell when the gun's bolt is closed. Since one should ALWAYS load an open-bolt SMG from a closed-bolt condition, it is necessary to download the mags by 1 or 2 rounds to facilitate insertion.
Note: Kurt Wala of KKF was killed in a motorcycle accident in March 2009. He was a
real innovator, and his presence in the marketplace will be missed.
KKF A3-L Flash Hider
This design from Kurt's Kustom Firearms is essentially an extended copy of the USGI M-16A2 "birdcage" flash hider. It was originally intended for permanent installation on a 14.5" M4 barrel, to bring it to a legal (non-NFA) 16" length. I figured a little extra length would be a good thing on the M-11/9's short barrel, to keep the shooter's off hand farther from the muzzle opening. I requested a custom version of the A3-L in 9mm and threaded 1/2"x28. Machining on the flash hider is very smooth and professional, in contrast to my earlier A3 Tac Brake which is somewhat crude and shows pronounced toolmarks around its circumference. KKF has invested in better machines and has refined his processes over the years, to the point that his work now is second to none. The A3-L ships with a crush washer for indexing on the barrel so the slots are in the proper positions. Flash suppression is good; shooting mil-spec South African (PMP) ammo out of the HRSC upper's 5" barrel eliminates any muzzle flash from the shooter's point of view. Instead of a fireball, only a few small sparks are visible to bystanders, and are of roughly the same brightness and quantity as the flash signature from the ejection port (see pic).
Smith Enterprises Muzzle Brake
This design from Smith Enterprises is arguably one of the most effective muzzle brakes on the market. It features three large ports on either side, with two forward-angled jets and six small vertical ports on top, and a solid bottom. It is available in several styles and thread patterns for AR-15s and M-1As. Mine was for the 9mm AR-15, but I ordered it custom-threaded to 1/2x28 for installation on the CAR-OPT upper. It performs very well on the slowfire-converted M-11/9, reducing muzzle climb to almost zero on short full-auto bursts. It does, however, increase the amount of blowback, which leads to the gun getting dirty more quickly.
Lage Mfg. Inc. Wraparound Grips
This grip, designed by Richard Lage, is constructed of a semi-rigid plastic and consists of a front/side component which wraps around the MAC's grip (mag well) and is held in place by a separate backstrap. The frontstrap incorporates coarse checkering and a single finger groove, and the side panels are stippled to prevent slippage. The backstrap features a more pronounced "hump" at the bottom, as well as a generous beavertail where the grip meets the gun's lower receiver. The result is a grip that feels less like a 2x4 and more like a real firearm, while allowing repeatable, ergonomic hand positioning. The Lage grip is available for standard M-11/9s as well as those that have been converted to take STEN magazines. A version is also available for the MAC-10 .45 and MAC-10/9.