Rifle Roundup: Comparing Pistol-Caliber Carbines

Rifle Roundup: Comparing Pistol-Caliber Carbines


Pistol caliber AR-15-style rifles have been around for decades, and there are now a number of different offerings. Not only is pistol ammunition cheaper than rifle ammunition, I have yet to hear of a range that didn't allow the use of pistol caliber carbines. These guns also have a utility beyond that of simple target shooting, namely self-defense. Depending on the caliber and load, you'll see an extra 100 to 300 fps boost when firing pistol ammo out of a carbine-length barrel.

The lack of recoil and quieter report not only make them great choices for new shooters but those of slight build as well. Let's take a look at a few of the most popular AR-15-style 9mm carbines on the market today.

Colt AR6951

The Colt 9mm is the original pistol-caliber AR carbine. The Colt 9mm is a straight blowback gun with a redesigned bolt carrier. The requirement for any reliable gun is a good magazine, and Colt engineers decided to use the Uzi magazine as the basis for their magazine design and to use standard AR-15 upper and lower receivers as a starting point.

Colt 9mm carbines have a large polymer case deflector at the rear of the ejection port, but that is the only external difference you'll see from a standard AR, apart from the pin holes in the magazine well. A steel block is roll-pinned into place in the magazine well of a standard AR-15. The top side has a feeding ramp as well as a fixed ejector, and the standard magazine release button works to drop the magazines.

I obtained an AR6951 to test. It has a light 16-inch barrel tipped with an A2-style flash hider, M4-style fore-end with fixed front sight post, flattop receiver and Magpul flip-up rear sight. The carbine comes with a standard A2 pistol grip and one of the new Rogers Super-Stocs, an improved collapsible model with a hard rubber buttplate.

I'm told that if you put enough rounds through a select-fire Colt submachine gun it will get dirty enough to start jamming, but truth be told I've never been able to get a semi-auto Colt 9mm carbine that dirty. What you will find, however, is that the Colt 9mm magazines are tough to load. The springs are so strong that getting more than 10 rounds into a magazine without a mag loader requires a lot of effort.

As these are submachine gun mags, they are fed from the top, not the front. To load them by hand you need to put the next round on top of the feed lips, hold it down with your thumb and then smartly smack the base of the magazine against something hard. The round will pop into place. The followers have a tab that will lock the bolt back on an empty magazine.

The carbine Colt sent me ran flawlessly, and the only complaint I had with it was the stock. The length of pull is adjusted by the use of a lever, which bears on a cross pin. The cross pin is supposed to be captured, but on mine it wasn't, so when I was adjusting the stock while it was tilted sideways the pin fell to the ground, rendering my stock (temporarily) nonadjustable. This was annoying, but it did not affect operation of the gun.


  • It's an original Colt
  • Ships with two 32-round magazines and Magpul backup iron sight


  • Rogers stock was defective
  • Magazines are extremely tough to load
  • Most expensive of any carbine tested

Rock River Arms LAR-9

Rock River Arms originally was in the business of making custom 1911s but moved into the AR market, including the LAR-9 9mm carbine. There are several different versions available, and I picked a LAR-9 CAR A4 model to test. This flattop model has a 16-inch barrel, M4-style fore-end and collapsible stock, fixed front sight, A2 flash hider and rubber pistol grip.

Unlike the Colt, the Rock River has a dedicated 9mm lower, with a magazine well that will accept only 9mm magazines. The LAR-9 is built on the Colt design, and will accept any Colt 9mm magazines. It is shipped with one magazine, and I received a converted 25-round Uzi magazine with my carbine. Uzi magazines are very reliable and easy to load to capacity by hand because they have lighter springs than the Colt mags, but they will not lock the bolt back.

The barrel of the LAR-9 is slightly heavier than that found on the Colt, although they have the same twist (1:10). Between that and the extra aluminum in the dedicated 9mm magazine well the Rock River weighs 0.2 pound more than the Colt at 7.1 pounds. This is heavier than a pistol caliber carbine needs to be, but it balances well. The LAR-9 comes with Rock River's improved Star selector, which is an improvement over the original design.

The trigger on the RRA LAR-9 (and the Colt as well) is typical GI, which means it is heavier and grittier than I would have liked, but hitting palm-sized targets offhand at 50 yards was easy. Try that with a 9mm pistol. The low recoil impulse also means you can hit a pie plate at 25 yards with every shot as fast as you can pull the trigger.

I ran several hundred rounds through the LAR-9 using both the supplied converted Uzi magazine as well as a Colt 9mm magazine, and it was boringly reliable with everything. It was also a lot of fun.


  • Price is $150 lower than the Colt
  • Comes in a lockable rifle case


  • Ships with only one 25-round magazine
  • No rear sight

Lone Wolf Distributors G-9

Lone Wolf doesn't offer complete carbines, but it sells a complete lower receiver and a complete upper receiver. I wanted to cover the company in this article specifically because it has a different goal: to make a reliable pistol-caliber AR-15 that uses Glock magazines.

The Lone Wolf G9 uses a standard Colt-pattern 9mm carbine bolt/carrier, slightly modified to work with Glock magazines. The firm will convert the bolt of your Colt, Rock River or other carbine to work with Glock magazines, as it only needs to be relieved slightly, so if you have a pistol caliber upper and don't want to buy a whole new gun you could go that route. The biggest differences are in the lower receiver.

I got a CAR A4-style G9 carbine for testing. This carbine was a little more tricked out than the standard model and had a 16-inch barrel with an M4 cutout, tipped with a muzzle brake (the standard upper has a flat top, A2 flash hider and quad rail for $650). It also had a rubber Ergo pistol grip instead of the standard A2 grip.

Carbines fed by Colt mags require a feed ramp between the magazine and the chamber, but the angle of the Glock magazines means that the rounds feed directly from the magazine into the chamber, with no feed ramp required. The bolt will not lock back on an empty magazine, but you can lock it back with the bolt catch.

Lone Wolf engineers designed a large serrated paddle-type mag release that works off the standard Glock mag catch cutout, and works with all generations of Glock magazines. Not only does this paddle mag release work well, it looks cool. As the carbine is fed by standard Glock pistol magazines, whether you have 10-, 17- or 33-round 9mm Glock mags lying around, they'll work in the G9. The lower receiver uses standard mil-spec trigger parts, including a 5.56 hammer, and a complete lower retails for $350.

The Lone Wolf G9 was completely reliable, but I would have been surprised if it hadn't been because of the Glock magazines. It was a little busier than I prefer (I have no fondness for quad rails, and the muzzle brake didn't really do anything as the pistol cartridges don't generate enough gas at the end of the long barrel), but I like the concept.


  • Fed by Glock mags
  • Controls identical to an AR-15
  • Magazine release an improvement over the original GI design


  • Not provided with any sights
  • Bolt doesn't lock back on an empty mag

JR Carbine

The JR Carbine is a straight-blowback pistol caliber carbine. While it will take AR trigger groups, stocks, pistol grips and fore-ends, one look at the carbine will tell you it is not designed around the AR receiver.

This carbine is very simple, and simple is good. First, it is designed around ultra-reliable Glock magazines. Second, both the charging handle and ejection are completely reversible. The handle simply unscrews. Moving the ejection port cover from one side of the receiver to the other changes the ejection because the ejector is built into the inside surface of the cover.

I obtained a 9mm carbine for testing, but they are offered in .40 S&W and .45 ACP as well. If you want to change calibers, you don't have to buy a whole new gun; you can buy a conversion kit for $250 that includes a new barrel and, in the case of moving from the 9/40 to the .45, a new magazine well.

To keep their carbine inexpensive ($699 for the basic model) the designers use a simple magazine release on the left side of the magazine well, similar to the layout you see on Glock pistols.

The upper receiver is secured to the lower with two hex-head screws. The bolt handle reciprocates when firing, and it can be locked back with the use of a notch. Both the upper receiver and fore-end are railed, so you can mount whatever optic you desire, but the carbine does not come with any sights.

I have fired three JR Carbines extensively, two in 9mm and one in .40 S&W. All of them were completely reliable. My boys and I ran at least 500 rounds through one 9mm, and it got so dirty I could barely work the bolt by hand, yet it still kept running. However, all three carbines suffered the same problem: The fore-ends got loose and unscrewed under recoil.


  • Inexpensive
  • Fed by Glock mags


  • Not an AR-pattern carbine
  • Fore-ends came loose under recoil


To be honest, I liked the looks of the JR Carbine the least of all the guns I tested, specifically because it wasn't an AR-pattern gun, and the looks (and balance) of the Colt the best. However, the tough-to-load Colt magazines frustrated me, and the broken pin in the stock was disappointing.

My two boys (ages 14 and 10) liked the JR Carbine the best because the controls were simpler. They liked the bolt handle on the side of the receiver. They knew right where it was, and with the notch it was easy for them to figure out how to lock it back.

Reliability wasn't an issue when it came to picking a favorite, as every carbine ran flawlessly, clean or dirty.

Converted Uzi mags to run the Colt or Rock River aren't hard to find, and 9mm Glock mags are everywhere, which is something to consider. But whatever your tastes, there's a pistol caliber carbine out there that's right for you.

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