November 17, 2014
Where home defense is concerned, AR-type carbines chambered in pistol calibers have several advantages over ARs chambered in .223/5.56 or any of the other popular rifle cartridges. Within the confines of a building, rifle cartridges—with their higher velocities and much greater propellant gas emissions—produce a far louder report than do pistol calibers. Fired from a 16-inch AR-15 carbine barrel, a 9mm cartridge is relatively quiet, as cartridges go. A .223 or 5.56mm cartridge fired from a 16-inch barrel is the opposite: loud and sharp, especially if, like so many ARs today, a muzzle compensator is installed.
Few homeowners responding to a bump in the night will use hearing protection, nor should they—hearing the next bump in the night may make the difference in successfully protecting hearth and home. Having a home-protection gun in a caliber that won't cause tremendous damage to your hearing when fired indoors is a bona fide advantage.
RELATED VIDEO: Guns & Ammo TV goes behind-the-scenes at Stag Arms to learn about their research and development.
Another huge benefit a pistol-caliber AR (especially 9mm) offers is the simplicity of its operating system. Unlike rifle-cartridge ARs, which operate off of a complex gas-impingement system that bleeds gas from the bore and feeds it back into the action to unlock and drive the bolt and carrier, 9mm ARs function via a simple blowback system. If you own a Ruger 10/22 rifle, you can mentally conjure a beefed-up version of its bolt, stuff it into an AR-like exterior, and you basically have your 9mm AR. There are differences, yes, but like the reliable 10/22, a pistol-caliber AR's breech is shoved open by the rearward thrust of the cartridge case itself. No gas tubes, no pistons long or short, no rotating bolt or locking lugs, no gas rings, just a simple, stout breechblock with a firing pin though it.
While a blowback system does allow some hot, dirty gases back into the inside of the action as the fired cartridge casing exits the chamber, the amount is relatively minor compared to the quantity of gas directed into the interior of the action by a standard gas-impingement system.
But I've pontificated on the virtues of pistol-caliber ARs long enough. Now on to the brand-spanking-new 9mm carbine by Stag Arms: The Model 9.
For shooters less familiar with Stag, it's a company that offers AR-type rifles of resounding quality but—usually—without unnecessary bells and whistles. I once roomed with a legendary gun writer who has penned several very successful books on AR-15s, and for conversation and enlightenment's sake, I asked if he were forced to choose one good AR—performance, reliability, and value being paramount—which manufacturer would he choose? The unhesitating answer was Stag Arms. I've since used Stag's guns extensively with never an issue, and the most accurate .223 rifle I own is a Stag Model 6 Varmint rifle. However, until now Stag hasn't offered any pistol-caliber ARs.
Model 9 Specifications
Built on a dedicated, 9mm-magazine-only lower receiver forged of 7075-T6 aircraft-grade aluminum, Stag's Model 9 isn't a converted .223, it's a full-time, 9mm-only carbine. As such, it avoids the pitfalls sometimes experienced when using a conversion kit in a .223/5.56 lower receiver.
Four variations exist. The standard Model 9 (MSRP: $990) and 9L (a true left-hand model; MSRP: $1,025) have no sights, while the Model 9T (MSRP: $1,275) and 9LT (MSRP: $1,295) come equipped with Diamondhead low-profile folding sights.
The most significant visual difference from a typical rifle-caliber AR is in the magazine well. Although the outside dimensions appear standard, the inside is milled for an Uzi-style 9mm magazine, leaving a significant amount of receiver material around the mag well. By the way, the Stag carbine comes with one 32-round ASC 9mm magazine. According to ASC's website, the mags are made of stainless steel with a self-lubricating, corrosion-resistant matte black finish. Ordered from ASC, additional magazines are $19.99, and I'm sure Stag Arms will carry them as well.
Another visual difference from the norm is at the ejection port. A polymer shell deflector is fitted over the rear portion of it. The rear portion of the dustcover is cut off to match. There is no forward assist on the upper receiver.
Aside from those differences, the exterior of the carbine and the fire controls are pure AR-15. The grip is an A2 type. The trigger is a standard mil-spec (reliable but heavy) unit. The trigger guard is the traditional straight version. The stock is Stag's standard six-position M4 type. A nice endplate at the rear of the upper receiver offers ambidextrous attachment loops for a single-point sling.
The upper has the now-common flat-top rail, and aligned with it is one of today's nicest cutting-edge handguards: the long, sleek, small-diameter VRS-T 13.5-inch-long model by Diamondhead, which sports a full-length integral rail at 12 o'clock, cooling vents, finger grooves down each side, and a smooth bottom for shooting off of bags. Threaded holes down each side and the bottom enable owners to attach sections of rail to which lights, lasers, and other accessories can be mounted.
Long slender rails are far more comfortable in the support hand than are typical quad rails, plus they assist in rapid target transitions courtesy of the down-barrel hold they offer. They also allow shooters to mount accessories wherever desired without cluttering up the rest of the handguard.
At the muzzle the Stag Model 9 sports a typical A2-type flashhider (with a 9mm hole in the middle, of course). The 16-inch 4140 chrome-moly steel barrel is chrome-lined and rifled with a twist rate of 1:10 inches.
Because it's a blowback action, no gas block and gas tube exist. What would normally be the bolt and carrier group is one hunk of 8620 steel; the boltface is milled into the front surface along with a slot for the fixed ejector to travel in, and an extractor is fitted. The extractor is fitted to the lower receiver. The firing pin and its securing key and a pseudo gas key fixed atop the bolt are the only other parts. As far as I can tell, the "gas" key wouldn't even be necessary if it weren't needed to connect the bolt with the charging handle.
At a casual glance the upper receiver appears to be stock AR-15, but closer examination reveals that no gas tube hole exists.
Although the trigger group and fire controls mounted on the lower receiver are standard AR-15 fare, big differences exist internally. At the front of the magazine well, a heavy, milled 4140 steel feedramp is fixed in place via a stout Allen-head screw. A large, hook-shaped ejector juts up from a slot in the rear of the mag well. Finally, the bolt catch is bigger than that on its .223-caliber sibling. And for those of you who are wondering, yes, it does lock the bolt open on an empty magazine, at least on the one that came with my review gun.
At the Range
After checking out the intriguing internals of the new Model 9, I put aside my eagerness to shoot it and took photos. Knowing that it would collect a lot of dust and grime during a long accuracy test and the reliability and manipulation drills that I intended to put it through, I preferred to photograph it clean.
With that finished, I mounted a 3-9X 40mm Leupold VXR scope suitable for accuracy testing AR-15 rifles and headed to the range. To test consistency coupled with precision, I fired three consecutive five-shot groups without allowing the barrel to cool with each of seven different types of ammunition. To my delight, group size and point of impact stayed the same as the barrel heated, although to be fair the 9mm cartridge doesn't heat a barrel nearly as fast as rifle cartridges.
I'm an admitted trigger snob and abhor standard AR-15-type mil-spec triggers. Like most, the one in the Model 9 was heavy and had gritty creep; particularly one big glitch, or "click," that occurred right before the trigger broke. Although I tried, it was too close to consistently stage through and then break the trigger perfectly cleanly, and I'm pretty sure accuracy—although certainly adequate—suffered.
Measured with my Lyman digital trigger-pull gauge, the trigger averaged 7 pounds, 7 ounces with 4 ounces of variation over a series of five measurements. That's too heavy for precise work. I presume Stag will offer $80 match-grade trigger upgrades to shooters ordering a Model 9 straight from the factory—as it does with most other models—and I'd heartily encourage taking advantage of that offer.
With accuracy testing complete, I switched out the optic for a compact little TruGlo Triton electronic dot sight—an optic more suitable for the intended purposes of the Stag Model 9—and ran casual drills with the carbine to evaluate ergonomics and rapid-fire capabilities. (See the sidebar on page 63 for more about this cool optic.) Double- and triple-taps on my Range Systems torso-size target were a breeze out to 40 yards or so, with shot string times quick enough that the echoes bouncing off the central Utah hills merged together. Stretching the Model 9's legs a bit, I was able to hit basketball-size targets out to 150-plus yards with surprising effectiveness.
Not surprisingly, the 9mm carbine feels very familiar to anyone well versed in standard AR-15s. Handling characteristics are much the same, although the sound of the shot is far quieter and recoil is almost nonexistent.
Throughout my testing, the 9mm carbine digested all ammo I fed it without a hiccup, even when I mixed various hollowpoints and full-metal-jacket rounds in the magazine and held the Model 9 at odd angles while firing. Stellar reliability, while predicted, is always a nice feature to corroborate.
Loading the ASC magazine was easy for the first 20 or 25 rounds, although care had to be taken to avoid getting the rim of cartridges hooked over the rear edge of the feed lips as they're pressed. The last few of the 32 rounds got pretty stiff, and you may need to use both thumbs to press them in.
Were this Model 9 mine, I'd swap out the mil-spec trigger for a good match-grade version, install a section of rail and a light on the handguard, and add folding back-up iron sights with a Trijicon front post equipped with a tritium insert (or just order the Model 9T with Diamondhead sights included to start with).
Within the ranges that such a firearm would likely be used for personal protection, all of the ammunition I tested would be plenty accurate. Given the increased velocity that the 16-inch carbine barrel generates (compared to the pistol-length barrels that most 9mm defensive ammunition is engineered for) and that the added velocity would cause larger than usual expansion and reduced penetration, I'd lean toward toughness and choose a load that passes the FBI protocol tests. Of those that I tested, the Hornady Critical Duty load and the Winchester PDX1 Bonded load would be what I'd stuff into the magazine for night watch.
There's one caveat to that. For use in a heavily populated urban environment — particularly for home defense in an apartment complex or whatnot — I'd choose a light, fast bullet that is likely to fragment in walls and stop rather than one that would continue through, potentially endangering neighbors.
I hope and pray I never have to raise a firearm in defense of life, but in the event that it did happen, with the Stag Model 9 I'd have a carbine ideal for indoor use. It's a relatively quiet, politely recoiling gun with a plentiful supply of projectiles suitable for facing a deadly threat.
The Model 9's
long, slender 13.5-inch Diamondhead VRS-T handguard
is free floating, has threaded holes along both sides and the bottom for attaching accessory rails, and feels great in the hand.
The most notable difference from the standard AR-15 is the Stag
Model 9's dedicated 9mm magazine well — no conversion kits employed here. Note also the polymer shell deflector at the rear of the abbreviated dustcover.
At the heart of Stag's blowback 9mm action is the bolt. It's a simple, heavy hunk of steel with a firing pin, an extractor, and a 'gas ' key to interface with the charging handle.
Dimensionally similar and sporting AR-type fire controls, the Model 9's lower receiver is internally very different from that of a standard AR-15. Note the fixed ejector hooking up behind the magazine well, the extended bolt catch, and the winged steel feedramp at the front of the mag well.
The Model 9 shot all seven of the factory loads the author put through it without malfunction and with more than acceptable accuracy.