The main thing about an AR15 pistol is that it’s a smaller platform that enables you to harness the firepower of a full-sized rifle platform in a much smaller footprint.
So as a general rule, smaller is better, right – and that should extend to barrels, right?
Yes and no. Here’s the breakdown on barrel length in AR15 pistol uppers.
About Shorter Barrels
AR15 pistol uppers are available with barrels in a range of sizes, from as small as 5” or 7.5” to 10” and even bigger.
The shorter the barrel, the lighter the platform will be. It will also be shorter and more compact overall. This improves concealment and makes these little platforms ideal as truck guns or stashing for defensive applications.
An AR15 pistol upper with a really short barrel will also potentially (but not always) offer superior handling. This can make them desirable for use in close quarters engagements.
It’s also the case that shorter barrels don’t necessarily present a compromise on accuracy. Most shorter barrels are manufactured with a tighter twist rate, like 1:5, to compensate for this.
Moreover, shorter barrels usually generate more consistent harmonics, which helps ensure greater accuracy – not that it even really matters at the ranges at which these platforms will be engaged.
Now for the not so good. Shorter barrels will invariably generate much greater muzzle pop and blast. This makes them annoyingly loud. You can suppress one, but then you’re going to need to be a lot more thorough in your cleaning, too.
Secondly, the shorter barrel doesn’t give the propellant charge enough time to deflagrate fully, which equates to two things.
One, shorter barrels run dirtier and produce way more fouling, which will get in the gas system and the action, too. The other is that shorter barrels don’t generate the same muzzle velocities as longer barrels.
About Longer Barrels
On the flipside we have AR15 uppers with longer barrels, in the area of 10” or 11”. You might also consider an AR15 with a 7.5” barrel.
The longer barrel will not offer concealment traits quite as favorable as builds with shorter barrels, but they are still quite compact.
On the same side of that coin, an AR15 pistol with a longer barrel will also not necessarily handle as well.
But there are advantages. One is that the slightly longer barrel gives the propellant charge more time to deflagrate. That means you get more power from the same loads.
The other is that it’s easier to configure builds with slightly longer barrels for consistency. Short builds are plagued with inconsistencies that don’t affect their longer cousins.
Still, the choice is up to you. There are benefits and drawbacks to each, and an AR15 pistol is an AR15 pistol.
Check Assembled AR15 Pistol Uppers at MCS Gearup
Not sure which size barrel or AR15 pistol upper you want to build with? There are obviously advantages to both short and longer barrels, and you’ll also have to make decisions about the gas system (if there is one) as well as about buffer weight, muzzle devices, and any other customizations you intend to make.
Check out your options online at MCS Gearup. They sell a wide range of assembled uppers and parts that you can use to customize your builds, in addition to buffer tube accessories, muzzle devices, handguards, and other AR parts. They also carry tons of other parts and shooting accessories in the mix.
