There's no denying the popularity of AR pistols. With a brace or other solution (later in article) the AR pistol provides the controls and parts interchange we're used to, but in a lighter, smaller, handier setup. The problem with most of them is what isn't seen; they're weak. This article will guide you through a parts list to build a 10" barreled pistol that hits HARDER than a 16" 5.56x45 rifle AND COSTS LESS to feed.
The weakness of the popular AR pistol is the caliber. 5.56x45mm is a lightweight cartridge that needs speed to make energy. The ideal barrel length for 5.56x45mm or .223 Remington is somewhere between 18 and 20 inches. A bit cumbersome. Popular rifles have 16" barrels, with pistols tending to have between 7" and 12" of barrel. What if we fixed the weakness issue by swapping to a less-expensive and less velocity-dependent caliber?
In the video below you'll see the math behind an inexpensive 10" built that beats most 16" rifles.
For the sake of logic we'll start at the muzzle and work our way to the end. If you're new to 7.62x39mm ARs, it's only the barrel, bolt, and magazine that need to be different. You may find buffer or spring tuning to help, but only those three parts are truly unique to the caliber.
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Muzzle Device: This build was meant to be suppressed from the start. 10" 7.62x39 is LOUD and fiery. While fun for the shooter (only), it's rather obnoxious at a public range. For that reason the YHM cage-type device is used over the QD brake when a suppressor isn't in use. Yankee Hill Machine appears to have stopped producing our particular device, just like they did our suppressor before the ATF even let me take it home. What ever you go with, some type of blast deflector is highly recommended.
Barrel: Quality 7.62x39mm AR barrels can be tough to find. With the barrel being the heart of any AR I didn't want to risk it with an unknown brand and so went with Diamondback. Every Diamondback AR I've reviewed has had superb accuracy, plus it was affordable, and nitrided inside and out. Unlike chrome lining which can foul rifling and wears with use, nitride coatings harden and coat the existing material. It can not be removed without removing metal and does not alter the dimensions of the rifling. I was excited to finally find a 7.62x39mm AR barrel I could trust.
Gas Block: Knowing this build would likely be going back and forth between suppressed and unsupressed an adjustable gas block was key. I wanted something with definitive adjustments (versus the screw type) so I could return to the setting I knew worked best. We've used the Patriot Ordnance Factory Dictator in the past, but it is lengthy and requires a taller handguard. This time we tried the Strike Industries Collar Adjustable Gas Block (CAGB). The CAGB installs easily though I bubba'd one of the clamping screws by thinking it could use a little more torque.
The CAGB has five positions and one completely closed setting and can be adjusted without tools (as long as it's not hot!). Once the shooting begins the tip of a round can be used to adjust.
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Hand Guard: Totally a personal preference, but I wanted something that gave me access to the gas block, looked good, and would provide plenty of air flow around the barrel. If you've spent any time with an AK you know how hot 7.62x39 can get! My choice was the 7" Cloak from DoubleStar. As you can see it turned out to be the perfect length. The anti-rotation tabs are a great feature as long as your upper receiver is milspec width. I had a spare billet upper receiver that I was unable to use unless I got to dremeling the Cloak.
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Optic: After using the Lucid Optics M7 red dot on several other guns, we put one on this one too. The reticle is smart, easy to use, and field of view excellent for such a compact optic. No magnification, just a usable reticle. We covered the M7 in more detail in an article here on GBGuns Depot.
Upper Receiver: Thwarted by the anti-rotation tabs of the Cloak handguard I had to stick with milspec width, but wanted something not so boring. A perfect place for the M4E1 from Aero Precision. Nicer lines, scalloped and T-marked rail, but all the rest "milspec". My original intent was to go without a forward assist, but during break in the forward assist proved helpful when dealing with lacquered-steel cases.
Bolt & Carrier: All you need is a 7.62x39mm bolt and a regular 5.56mm carrier, but I opted to go with a complete and dedicated BCG from Fail Zero. This setup also includes an enhanced firing pin for increased reliability with the caliber and harder primers. I've not tried the brand before, but am impressed with their nickel boron coating which makes cleaning a lot easier, provides some lubricity, and looks great. After a couple hundred rounds the bright color had tamed to a more mellow stainless look. It took only wipes to clean it decently enough to put back in the gun.
Charging Handle: This was our first time really testing the Gas Defeating Charging Handle (GDCH) from SilencerCo. Wow, what a difference! The trick with this one is a small gasket-like arch that helps seal between the charging handle and upper receiver. Conventional theory was that gas leaks above the charging handle, but this thing works! Not only does it make shooting suppressed MUCH more pleasant, but much less health adverse. Those gasses sting for a reason, they're filled with toxic chemicals! Do yourself, friends, and family a favor if you use a can. They're not cheap, but neither are lungs and eyes.
Lower Receiver: The cool swoopy cuts of the Diamondback Firearms lower receiver we used serve a functional purpose too. The shorter magazine well shaves a little weight, but more importantly allows for easier magazine insertion and clearance of any serious malfunctions. It's the same advantage afforded by the Thunder Ranch AR lower receiver made by Aero Precision. Unfortunately, at the time this article was written I was unable to find our exact model available as a separate lower. The good news is you don't need a special lower for a 7.62x39mm AR. Barrel, bolt, and magazine are the only caliber-specific parts.
Trigger: Standard-to-extra-power springs are a good idea, but at the sacrifice of feel. I took my chances with a Rise Armament 434 trigger which (with the Fail Zero firing pin) seems to be fine with some Russian ammo, not with others. The saving grace is we won't see much Russian-made ammo in the future. We had issues with Red Army Ops (no longer available) and some Golden Tiger (known for hard primers) but no issues with Read Army Standard white box, and no issue with brass-cased ammunition. Though not always hard-enough hitting for all 7.62x39mm ammo, it's hard to give up the crispness and short reset of the Rise Armament RA-434.
Buffer: Without much prior experience doing a build like this I looked to what I know works in other complete guns. That lead me to my PWS lower (for a 10~" piston upper) which of course uses their Enhanced Steel Body H2 Buffer. The body has flutes which may or may not help with anything, total weight is 4.5 ounces. So far it seems to work in this build, but of course the adjustable gas block is helping me solve buffer issues. Were I to have run out of gas adjustment changing buffer weights would be the next step. Fortunately this works.
Stability is a function of safety. I don't care where you stand on the political line, it's vital that a firearm be stable enough to ensure good sight alignment and that rounds go where intended. I tried to different pistol lowers with this build. The one in the main image has the Tailhook Mod 2 (adjustable) from Gear Head Works. The adjustability helps compensate for different arms lengths and shooting positions.
The other option, and potentially most future-proof, is the Pistol Storage Device. We've covered this ingenious device in the past. It's not a brace, not a stock, and has its own unique approval letter from the ATF. Appropriately named, this device serves as a place to tuck away a sling when not in use or carry a spare magazine. Some assembly is required, but that's so you can configure the storage capacity to your needs. Video explanation of the Pistol Storage Device below.
With this parts list you can build a very similar pistol and clang steel (or other targets) harder than your friend's 16" 5.56x45, spend less shot per shot, and have an easier time yielding it. I'm sure some of you have done similar builds, if so let us know what worked best for you in the comments section below.