One of the last daring designs to come out of Colt turned the gas-operated .223 Stoner carbine, what we call the AR-15, into a blowback 9mm carbine. Man, that gun—and other makes attempting the same design—was fun. But it was a mass of compromises. Today, Stag has taken the touchy 9mm carbine and turned it into a wonder with the Stag Arms Model 9.
The Stag Arms Model 9 is a 9mm carbine that looks a lot like the old Colt carbine but has none of the faults or shortcomings of the earlier carbine’s compromises. At first glance, it simply appears to be a standard AR-15 type rifle. It has the basic flattop upper receiver—a 7075-T6 forging, machined in-house at Stag and then hard-coat anodized to the proper mil-spec Type III standard. The Stag Arms Model 9 sports a carbine-length barrel with M4 handguards, a gas block with a 1913 rail on top and standard A2 pistol grip and M4 stock.
Basically, the Stag Arms Model 9 looks like a Stag Model 3 but with M4 handguards. But then you note the prominent case deflector, short ejection port cover and lack of a forward assist. That’s when you know you’re looking at a whole different animal.
A 9mm bolt, lacking the forward assist ratchets, does not need a forward assist on its upper, so Stag left it off because that means fewer parts to install, fewer parts that could cause you problems and less bulk overall. But the dimensions of the rest of the exterior are absolutely standard, so you can install whatever sights, lights and other accessories that you want—as well as swap out any of the furniture you want to replace.
On the inside, The Stag Arms Model 9 is like every other Stag AR ever made, which is to say it is well-built. The barrel is a 4140 steel tube, button-rifled to a twist of 1:10—which will stabilize even the 147-grain subsonic loads—and given a chrome-lined interior and a manganese phosphate exterior.
The receiver is a standard double push pin, small hammer-trigger pin lower, but with a difference. And that difference is just the start of where Stag improved on the old. The original 9mm carbines used filler blocks to remake the magazine well of the AR lower—one proportioned for a magazine to hold .223/5.56 ammo—into one that secures a 9mm magazine in place.
Almost 30 years ago, I had an AR 9mm carbine that was made to run with Sten magazines. They were about a dollar each back then, and it was a horrible way to do things. Mine ran fine, but I saw few others that did.
Colt decided to go with a modified Uzi magazine, but instead of doing the full engineering workup to make it run right, designers modified the magazines to ease the task of designing and building the carbine. The filler blocks were cross-drilled and pinned into the lower receiver, and depending on how diligent the driller was, they were in the right place, more or less.
Combine maybe-correct blocks with sometimes dodgy magazines, and the Colt would either run just fine or be a real pain in the neck. Further, if you dropped a loaded magazine, half or more of the rounds would squirt out on impact. I’ve had Colt magazines partially self-unload just while I was holding them.
What did the company do on the Stag Arms Model 9? Well, first, it altered the magazine well of the lower, broaching it specifically for a 9mm magazine—a simple step if you are a dedicated designer and manufacturer. The magazine well won’t hold anything else, and it is solid aluminum—no block-filling gaps. Then, Stag fixed a feed ramp into place on the lower to guide the rounds out of the magazine and into the chamber.
At the rear of the magazine well is a fixed-blade ejector to toss the empties overboard. And last but not least, engineers went with newly designed magazines from ASC. Not only are they of new design, but also they’re made of stainless steel and lock the Stag Arms Model 9 open when they are empty.
Of course, the lower isn’t of much use unless the upper is working with the rest of the team, so Stag built a tank-tough upper. The bolt on a 9mm AR is different from a 5.56 because as a blowback design there’s no need for a rotating bolt, so the carrier is simply machined as the bolt.
Think of a regular carrier, but when it comes time for the factory to bore out the bolt tunnel, the folks at the factory simply machine a breechface for a 9mm case head. The extractor is held in the carrier, and the firing pin works just like the one on a 5.56 carbine except there is a firing pin rebound spring inside of the bolt.
The 9mm bolt/carrier has a key on it, not unlike that of the 5.56, but it has nothing to do with gas. It is simply there to keep the carrier properly oriented inside of the upper. Without it, the bolt could rotate inside the receiver, and that would be bad.
Since the chamber is just that, the chamber, and there is no room or need for locking lugs and such, a 16-inch barrel on a 9mm carbine appears to be a bit shorter than a 16-inch barrel on a 5.56.
The Stag Arms Model 9’s buffer tube has the normal spring and buffer weight, and the lower has a normal hammer, trigger and disconnector. The Colt had a special buffer weight—one made as heavy as possible—and the hammer had a special design. If you tried to swap out the 9mm-specific Colt hammer for a normal one, you often ran into reliability problems.
On the Stag Arms Model 9, if you want to install a match trigger, you can select from any one of the seemingly hundreds available, as they will all fit. And if you want to fine-tune it for felt recoil, you can swap buffer weights of differing masses to your heart’s desire.
Loading is simple since the magazines are double-stack and double-feed. They load easily enough, although you will encounter increased resistance as you get more into the tube. Recoil with a 9mm carbine is an interesting experience. Yes, it is “only” a 9mm, but you don’t have any of the recoil reduction of a gas system to help you. So with some loads and some buffer weights, recoil can be more than a bit bouncy. But if you settle on a particular load, you can tune the Stag to be soft in recoil.
Noise is a different and much more pleasant experience. Where a .223/5.56 carbine can be obnoxiously loud, a 9mm out of a 16-inch barrel can be downright quiet. If you use a normal charge of fast-burning pistol powder, you have a very low pressure at the bullet’s uncorking. If you load heavy bullets, you can even get rid of the supersonic crack.
And for those who have such wondrous devices, a suppressor can then take the rest of the drama out of shooting a 9mm carbine. Indeed, you can make the entire affair so quiet that the loudest noise going on is the bolt clacking back and forth.
Accuracy is simply brilliant. My Stag Arms Model 9 shot everything well, but some particular loads were amazingly accurate. Hundred-yard steel plates? No problem. Clay pigeons lying on the hillside? Piece of cake. For the run-and-gun drills and just fun shooting, I tried both an EOTech and a TruGlo on the flattop receiver and blasted away until I was grinning. For accuracy work, it was a simple matter to take a Weaver 1-5X scope with a Weaver QD mount and install it on the Stag Arms Model 9.
Okay, so this is fun to shoot. But what else? What advantages does the Stag Arms Model 9 offer over, say, a 5.56 Stag carbine? First is cost. Ammo prices are coming down, but 9mm is still cheaper than 5.56. And if you reload, you can drop prices even more. Last I checked, you can reload 9mm for less than half the cost of new .223/5.56 ammo, and when it comes to reloading, 9mm is a significantly less difficult caliber to reload than .223.
Next up is range utility. There are ranges, mostly indoor, that are not happy about rifles. If you can shoot a handgun there, you can shoot a Stag Arms Model 9 there—and at closer distances than a .223 rifle would be allowed, too.
For home defense, a 9mm carbine offers a lot. The softer recoil, lower noise and ease of handling of ARs in general puts a Stag Arms Model 9 on the first page of choices. Next, it will work with all the usual high-tech hollowpoint defensive loads, and you’ll get increased velocity as well—depending on the powder used in a particular load. With faster-burning powder, you’ll see minimal velocity increase when you go from, say, a four-inch pistol to a 16-inch carbine, but with slower-burning powder, you can gain as much as 200 fps.
When my gun club began 3 Gun competition, we shot 9mm carbines as well as other rifles. Then we began using them in our regular IPSC handgun matches. What we found was that a C-class shooter firing a 9mm carbine could give an A-class shooter with a handgun a hard time. If the carbine shooter put a red-dot sight on his 9mm, he could beat the times and scores of anyone in the match, even the club champion. That’s how much of a speed and accuracy advantage a 9mm carbine has over a 9mm handgun.
Someone is sure to complain that by making the lower 9mm-specific, Stag has made it impossible to rebuild the Model 9 to a 5.56. Why would anyone want to? Given the current price range and availability of AR-15 rifles, just buy a whole .223/5.56 rifle instead of the parts and hassle to rebuild the Stag Arms Model 9.
The Stag Arms Model 9 can also be had with the clever and handy Diamondhead VRS-T free-float handguard. And because it’s a Stag, it’s also available in a left-hand version. The Model 9 is fun to shoot, economical, accurate, fast and able to accept all the normal accessories—and unlike past Stoner 9mm carbines it’s totally reliable and not the least bit fussy. What are you waiting for?