AR pistols have only surged in popularity over the past ten or so years, with that tide showing no signs of abating.
If you’re here because you’re considering an AR pistol build, here are some things to hammer out.
Why an AR Pistol?
An AR pistol is not an SBR (short barreled rifle) which is an NFA weapon and requires a special tax stamp and permission from the ATF.
Rather, an AR pistol is designed to be a pistol from the start; it has a short barrel (like a pistol) and has no stock. Often, AR pistols are outfitted with pistol braces which help the shooter stabilize them.
Some shooters prefer the AR pistol to the rifle because AR pistols are often built in the same chamberings, but are far more compact and more concealable. This makes them better for defensive applications or vehicle carry, for instance.
Others just enjoy the fun of tinkering, but if you’re looking into an AR pistol build, there are some things you’ll have to take into consideration.
What Is the Best Caliber for an AR Pistol Build?
One unique aspect of AR pistol builds is that the builds often revolve around the same calibers as full-sized rifles.
This presents both opportunities and difficulties. On the one hand, it gives you the flexibility to customize a pistol in a rifle caliber; on the other hand, controlling that recoil is serious.
Choose the caliber based on what you expect to use the AR pistol for. For instance, 5.56 NATO is low-cost and low-recoil, and it can be used for a whole bunch of sporting and defensive applications.
At the same time, there are AR build kits out there in bigger calibers, such as 7.62x39 and .300 BLK. These calibers are heavier-recoiling, but produce far better stopping power, especially up close.
There are also pistol-caliber AR pistol builds out there. Consider, for instance, our 9mm AR pistol upper, which is appropriately chambered and sized for defensive applications - or just for high-volume target shooting.
There is no single “best” AR pistol caliber. Just make sure you choose one that works for your intended application.
Should You Get a Pistol Brace?
In recent years, the issue of AR pistol braces has been a contentious one. For a long time, they were considered legal and lots of shooters appreciated them because they provided a lot of extra stability, especially when firing an AR pistol in a heavy chambering.
Then there were some legal hiccups, but currently, as a result of the Fifth Circuit Court of Appeals’ November 2023 decision, pistol braces are back for the time being.
We sell them here, and they’re great for helping to corral the recoil of AR pistol builds, particularly in instances in which you’re shooting something like a .300 BLK or a 7.62x39mm that produces a lot of recoil.
AR Pistol Builds and Upper Length
There are lots of barrel lengths available in AR pistol builds, but some of the most common are 10.5”, 7.5” and 5 inch AR pistol uppers.
There’s something important you need to keep in mind when you’re looking at the specifications of an AR build kit. Barrel length (determined partly by upper length) is one of the most important determinants of AR pistol performance.
Here’s how it goes. The longer the barrel of an AR pistol, the more power the pistol will be able to deliver. In general, a longer barrel will produce more accurate shots, too, especially at ranges greater than 100 yards. Not that many people are shooting at these ranges with an AR pistol, but it is something to keep in mind.
The shorter the barrel, the less time there is for a bullet to accelerate out of the barrel. With extremely short barrels, such as with a 5 inch AR upper, the bullet will likely leave the barrel before all of the powder has even burned.
Which means these AR pistols will produce more fouling and require more frequent cleaning, as well as that they will not produce the same power as their counterparts with longer barrels.
A shorter barrel is not unequivocally a bad thing, though, as the shorter the barrel is, the more maneuverable and concealable the platform will be, increasing its suitability for close engagements.
Most people consider a 10.5” AR pistol barrel to be the optimal size for power and accuracy, but it lacks a little in terms of maneuverability.
On the other extreme, a 5 inch AR pistol upper will be far more maneuverable, making it better for home defense, but it will also be harder to control, will produce a lot of fouling, and will not be as accurate.
As a result, some shooters opt for 7.5” AR uppers, which offer a solid compromise in terms of power, accuracy, and handling. They have many of the virtues of both 10.5” and 5 inch AR uppers.
Micro Buffer Tubes: Short Buffer Tube Systems and AR Pistol Performance
Most AR pistol builds either come with micro buffer tubes or are compatible with them. The purpose of the micro buffer tube in an AR pistol is the same as it is in a full sized rifle.
It absorbs some of the recoil of the shot and houses the buffer weights and buffer spring, which serves as the return spring to push the bolt carrier group back into battery.
While you might theoretically be able to use a larger buffer with an AR pistol, that defeats the purpose of building an AR pistol in the first place. The whole idea here is to make a shorter, lighter, more compact footprint - so even if a pistol would cycle with a carbine or rifle buffer, why would you want that?
This is the reason that so many AR pistols are built with micro buffer tubes.
Do You Need a Short Buffer Tube System with an AR Pistol Build Kit?
Actually, not necessarily. If the AR15 pistol upper has a gas system, then yes, it will need a buffer tube that is appropriate with it - such as a short buffer tube system.
However, some AR pistol uppers do not have gas systems. The 9mm pistol upper we featured above in this article actually has a blowback action, not a gas impingement action, so no short buffer tube system is needed - in fact, no buffer system or buffer tube kit is needed at all.
Instead, the blowback cycles the action, bringing down the overall length and compactness of the footprint of this AR pistol even further.
Start with an AR Pistol Build from MCS Gearup
Still have questions about what parts to use with your AR pistol build, or what caliber to build it in? Get in touch with us at Sales@MCSGearup.com and we would be more than happy to help.