September 2016

5.56mm Pistols from Kel-Tec, Spike’s Tactical, and CMMG

We tried out three semi-auto pistols chambered for the AR-15 rifle round, from a full-out custom build to a no-frills polymer model. Tested: the PLR-16, The Jack, and the Mk4 K.

5.56mm Pistols from Kel-Tec, Spike’s Tactical, and CMMG

The Kel-Tec PLR-16 was the least expensive and most compact and lightest AR style pistol tested. It had an initial malfunction, but eventually performed, rivaling the accuracy of the pricey Spike’s Tactical The Jack custom build and the CMMG Mk4 K.

It could be argued that the AR pistol evolved out of a desire and need for shooters to own a legal short-barrel rifle-caliber weapon without having to jump through BATFE hoops or pay for a tax stamp to own an SBR (short-barreled rifle). The difference between an AR rifle and pistol comes down to the pistol not being compatible nor able to attach a stock. We wanted to take a look at these AR pistols for home defense and other uses where a compact firearm makes sense, because they offer a number of benefits over a conventional AR rifle, mainly, being more maneuverable while being chambered in a rifle caliber and being compatible with common AR-15 magazines. We acquired three examples, a Spike’s Tactical The Jack custom build, a CMMG Mk4 K, and a Kel-Tec PLR-16. The Spike’s and CMMG are true AR-15 mechanisms reconfigured to a pistol, while the Kel-Tec uses a different operating mechanism. All three are chambered in 5.56mm NATO/223 Rem. and all are compatible with AR-15 magazines.

We tested these pistols for accuracy, performance, reliability, compatibility with a range of AR-15 magazines, maintenance, ability to be customized, and cost. We found that the Kel-Tec was inexpensive compared to the CMMG and Spike’s Tactical pistols. The Kel-Tec, however, needed to be operated differently. The CMMG and Spike’s were an easy transition from AR rifle to AR pistol. An AR pistol, as we found out, is nearly as effective as a full-size AR at close to mid range. With the right ammunition, they could be tuned to be a very capable home-defense choice for anyone in the family competent to operate a firearm. Namely, using frangibles to limit overpenetration through walls and doors while still supplying lots of pop.

The AR pistol’s edge is its size, but it is also a disadvantage, as an AR pistol is not as easy to shoot as a rifle or a traditional handgun. They are large and require two hands to effectively deliver accurate shots. You could get off a few shots holding an AR pistol with one hand, but the weight of the pistol causes muscle fatigue. A typical full-size handgun may weigh more than 2 pounds loaded, compared to these AR pistols, which weighed from 3.2 to 6 pounds unloaded. Add a pound or more for a 30-round magazine, and you’ve got a sidearm that would wear out nearly anyone who didn’t transport them with a sling, just as you would with a rifle. We used one of the SIG SBX Pistol Stabilizing Braces ($149; and found we liked to use the brace differently than intended, which we will get into shortly.

We also fired the pistols using a Blackhawk Storm Sling ($33.95;, a single-point sling with a built-in bungee cord, which many team members felt was an excellent way to carry and control the pistol. We tested with three different AR-15 magazines, including a Brownells USGI CS (; $14) constructed of aluminum, and two polymer magazines, the Magpul PMag Gen2 (; $12.30), and the FAB Defense Ultimag (; $25). For fast reloads, we also used a Kydex AR magazine carrier from IBX Tactical (; $35).

Building an AR pistol is not just a matter of installing a short barrel in a upper receiver and swapping out the receiver extension/buffer tube. Short barrels lose velocity and provide less dwell time for the projectile, so manufacturers need to tune and time the mechanism. A short barrel also needs to work on a range of loads from low- to high-quality ammunition. Reliability can be an issue.

Hands down, the CMMG and Spike’s offered more customization than the Kel-Tec because they are compatible with a range of AR-15 aftermarket products — triggers, rails, pistol grips, BUIS, and more. The Kel-Tec is not as compatible. Also, for those testers already familiar with an AR-15, the CMMG and Spike’s were much easier to maintain. But there’s much more to consider, which we relate below:

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