AR-15 Pistols: Choose the Best Calibers, Setups, and More

The AR-15 is America’s rifle, like the M1 or the Kentucky Long Rifle before it -- the AR-15 is simply in a class of its own.

One of the best things about the platform is just how many forms it can take and how much freedom it gives you.

And one of the best of those is the AR pistol.

I’m sure you’ve heard of it, a short-barreled AR-15 style firearm without all of the extra paperwork and money of a true SBR.

But what does it really mean? Can you buy one? And how is all of this legal anyhow? We got that information and more down below!

What Is The AR-15 Pistol

The AR-15 pistol is exactly what it sounds like, an AR-15 but legally a “pistol”.

Really -- what this comes down to is making clever use of legal definitions to bypass the National Firearms Act.

To be clear: this isn’t a loophole, this is using the law as it is written. Perhaps not as it is intended, but definitely how it is written.

The fundamental characteristics of an AR pistol are pretty simple: a barrel under 16-inches and a pistol brace instead of a rifle stock.

Everything else is exactly like a normal AR-15.

“Pistol” Vs. “Short Barreled Rifle”

Practically speaking there really isn’t much difference. Really, the biggest difference is the brace instead of a stock. But with the current generation of braces, even that gap is very small these days.

“Short Barrel Rifle” is an NFA term that requires registration with the ATF, a $200 tax stamp, and a detailed background check. You’re also required to inform the ATF with an official form if you take your SBR out of state. Oh, and there is the 6-month to 18-month wait time to get approval to even build/own the rifle to start with.

All of that to say… that’s why pistols are so attractive. You get the same maneuverability, the same compact form, and the same punch, but for $200 less, no months-long wait time, no extra background check on top of the background you already get when buying a lower, and you don’t have to play “mother may I” if you want to go across state lines.

A Rifle is a Rifle, Always. But a Pistol can be a Pistol or a Rifle

This is another one of those weird legal things that sounds silly, but it’s the law so you need to know it.

A firearm built into being a rifle must always be a rifle. So if you take a complete lower with a stock or a brace and throw a 16” complete upper on it, it’s a rifle. Forever. Period.

If you replace that upper with an upper shorter than 16” then it is an SBR. Even if you also replace the stock so that it has a brace, it’s still an SBR since it was already a rifle and it can never be a pistol.

However, if a firearm is built as a pistol -- then it can become a rifle and go back to being a pistol with no problem.

Take a complete lower with a brace and add a complete upper with a shorter than 16” barrel, and you have a pistol. You can add a 16” or more upper to that and then switch back to your short upper while still having it stay a “pistol”.

Is that the dumbest thing you’ve heard this week? Well, it’s the federal government so… are you really that surprised?

Will These Stay Legal?

The short answer is that we don’t know. There is a strong push from the current administration to ban AR pistols and pistols like them. The ATF is in the midst of trying to redefine them and there are suggestions of congress trying to amend the NFA.

But, for now, at least, none of these things are actually happening. They might happen soon or later in the term, but for now -- we’re okay.

If these efforts come to pass we have no idea if there will be some kind of grandfathering or what will happen to current owners.

About the only guarantee in all of this is that if it happens, there will also be a long court battle soon afterward.

I feel confidant recommending AR pistols because they are outstanding tools and because I do not believe that the ATF has a legal leg to stand on. I strongly believe that the law is on our side, even if the government makes it difficult.

Shouldering Your Brace

Something that is a bit outdated is people saying you can’t shoulder your brace. While that was true for a while, it hasn’t been a thing for a long time now.

Back in 2017 the ATF released a letter stating that you CAN legally shoulder an AR-15 pistol with a pistol brace on it.

So there it is. Go for it!

Best AR Pistol Calibers

5.56 NATO

The classic is still awesome even with a shorter barrel. Just know that you’re giving up a lot of ballistic potential with a short barrel 5.56 pistol.

This is totally fine for short ranges like home defense, but trying to hunt with it or reach out can be a real issue.

Also, note that fireballs will be bigger and meaner the shorter you go. A suppressor is ideal, but a linear comp is a decent second if that’s all you can do.

300 Blackout

Designed for short barrels, 300 Blackout is really one of the kings of the AR pistol world. Perfect for suppression, complete powder burn in just 6-inches, it’s pretty awesome.

While you can go super short at 6”, I like to stay over 9” just to make sure you have enough handguard to grip and you run supers with a little less concussion blast.

Again, a suppressor is wonderful but a linear comp is basically required otherwise. [Check out our 300 Blackout Uppers and 300 Blackout Pistols!]

6.5 Grendel

This one might surprise you since this is normally a “long range” AR-15 caliber. But shockingly, 6.5 Grendel does really well out of a shorter barrel while still giving you a lot of range.

A 6.5 Grendel pistol wouldn’t be my choice for home defense, but if you’re looking for a small and really handy hog gun, then a 12” Grendel is a heavyweight contender.

Shorter than 12” and you lost a lot of punch, but even at 12” you save a ton of weight and gain a lot of maneuverability over a 16”+ setup.

458 SOCOM / 50 Beowulf

They’re big, they’re bold, and if the bullet won’t stop your target, maybe the concussion will!

Ballistically these are basically the exact same thing but with 50 Beowulf having a slight edge over 458 SOCOM.

Both work well out of short barrels down to about 10”, but both also give you a LOT of concussion.

If you can suppress them, it works well. If not though -- I honestly wouldn’t recommend this unless you have a foolproof way of having earpro with you when you encounter the bad guys.

Ballistics

So we’ve talked about the fact that you lose power with a shorter barrel, but how much do you really lose?

Generally speaking, and I mean very generally, you should expect 30-40FPS lost per inch of barrel for 300 BLK. 5.56 NATO, very generally, expect 50-70 FPS lost per inch of barrel.

Drop graph of M193 5.56 NATO and 300 BLK out of rifle and pistol length firearms.

Take those numbers with a grain of salt because there is a lot of factors that go into it.

M193 out of a 16” barrel has almost as much energy at 100 yards as it does from a 12” barrel at the muzzle (985 ft.lbf vs 992 ft.lbf).

300 BLK changes a lot based on ammo that is moving at supersonic speeds, but if you’re looking at subsonic ammo -- it is basically the same since that has a cap of about 1100 FPS.

If 1100 FPS comes out of a 16” barrel or a 10” barrel, it doesn’t matter -- speed is speed. That is one of the reasons why 300 BLK is such a great caliber for a pistol.

Practical Applications

Home Defense

The best and biggest way to use an AR pistol is for defending your home. Unless you live like a televangelist, you probably have some blind corners, hallways, and at least one bookshelf filled with nick-nacks that might get knocked over if you had to clear your house with a long rifle.

Now to be fair, door-kicking dudes overseas were clearing thousand-year-old mud huts with 20” barrels for most of the Global War on Terror, but it’s a lot easier with something a lot shorter.

If you live in an apartment or anything on the smaller side, a shorter barrel becomes even more important,

Hunting

This might not be what most people think of when they think short barrel, but I maintain that it has a lot of merits.

Hogs, coyotes, bobcats, and more are often found at fairly short ranges and just need to get got. A 12” 6.5 Grendel is perfect for it. So is a 9” 300 BLK. These are short, easy to use, and really handy.

Just make good ammo choices and understand that you have a lot less range than their full-sized brothers would have.

SHTF / Truck Gun

To be clear -- I am against the idea of a truck gun. This is a great way of giving your guns to bad guys who break into your car.

But, if you are a truck gun guy or maybe you legitimately need a gun you can throw in the truck for a day of work like doing land management, then a short barrel AR pistol can be perfect for you.

Easy to get in and out of the truck, decent ballistics, and it’s handy to walk around with if you need to.

If the world ends -- I don’t think many of us will be super worried about barrel length laws, but just in case the government comes back then you’ll be on the right side of the law with your pistol brace.

Short rifles are easier to use, easier to walk with, and are still just great options for… everything.

Build or Buy?

This is really no different than building or buying a normal AR-15. Except, since pistols have some strange rules about them -- it might be easier to just buy one and upgrade it as you see fit.

Buying your pistol means you don’t need to worry about was it a rifle or pistol first, or worry about if your brace isn’t the perfect brace.

That said, if you’re working off of a virgin receiver or maybe even an 80% lower, building your pistol is super easy.

If you get a complete upper, then just throw it on and you’re good to go.

If you’re building the upper also, remember that there is no difference in building it. No special tools, nothing weird to remember, just a shorter barrel.

Final Thoughts

Right now the AR pistol is legal. I hope that it stays that way for a long time to come, but only time will tell. What I do know is that AR pistols are not a fad and having easy access to a shorter AR is a real gain to the firearm community.

From home defense to hunting to the collapse of civilization, a good AR pistol is something we can all make use of.

[We'd like to thank David Lane for his hard work and research on this article! For more helpful guides check out our articles comparing 308 vs 5.56 and AR10 vs AR15s.]