If you’re in the market for a pistol-caliber carbine, do the pros outweigh the cons?

Should You Buy A Pistol Caliber Carbine:

Cons:

  • Marginal velocity improvement
  • Added weight to shoot a pistol cartridge
  • Over penetration issues
  • Pistol caliber ammunition heavier than rifle
  • Bolt and buffers heavier in AR versions

Pros:

  • Common ammunition for pistol and rifle
  • Compatibility between pistol and rifle magazines
  • Economical ammunition
  • Highly suppressible
  • Honestly, they’re fun

ARs truly are a platform of customizable wonder. Today, you can have an AR in a variety of calibers, from .17 rimfire up to several centerfire rounds in .50 caliber. Particularly popular, and gaining more fame all the time, are the pistol-caliber ARs, available in 9mm, .40 S&W, 10mm and .45 ACP. Should you have a pistol-caliber AR? That depends on several factors, such as use or application. And, we can’t discount the fun factor, the unique design and its historical significance.

It might be necessary to transition to the handgun, but you can still use the light mounted on your AR. The key to this technique is knowing how to shoot and manipulate your handgun using only one hand.
It might be necessary to transition to the handgun, but you can still use the light mounted on your AR. The key to this technique is knowing how to shoot and manipulate your handgun using only one hand.

Colt’s 9mm AR — SMG R0635 — was introduced in 1982. The original goal was to use as many standard AR parts as possible. After extensive testing and changes, Colt settled on a blowback system, as opposed to the gas-impingement system in the M16/AR15 — and a closed-bolt design, instead of the open-bolt design first envisioned. It did, however, use a standard M16/AR15 lower receiver with an adapter that accepted modified 9mm UZI magazines; a groove was added to the mag body so the bolt locked open when empty. At the time, the sub-gun market was dominated by H&K’s MP5, and the handgun-caliber AR never really took off. In the last few years, however, the handgun-caliber carbine has gained new traction, and today there are a lot of options available for this platform.

The question — as always — is a simple one: Do you need one? I usually start by comparing the disadvantages and advantages of a platform. Sometimes a weapon fits a specific application, or sometimes it’s something that would just be fun to own and shoot.

Disadvantages Of A Pistol-Caliber AR

The benefits of using a carbine in a rifle caliber are many. At the top of the list are the ballistic advantages. A rifle round is much more accurate, especially at extended distances. In the terminal ballistics category, the rifle rounds do a much better job of stopping the threat. Velocity is the key: A 55-grain 5.56 NATO round moving at 2,800 fps dumps a lot more energy on the target than a 230-grain .45 ACP bullet traveling at 900 fps.

A pistol round simply doesn’t have the energy to do the job, and this is true regardless of barrel length. With a pistol-caliber AR, you have a rifle platform — basically the same shape, size and weight of an AR carbine — but without the benefits of accuracy, distance and stopping power.


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Although the pistol round is moving slower, you have to worry about it over-penetrating more than the .223/5.56 round. Pistol rounds will penetrate more tissue, sheetrock and wood than the .223/5.56. This has been well documented. A pistol-caliber AR has less stopping power, and the chances of over-penetration are higher.

Compared side-by-side, round-to-round, pistol-caliber ammunition is heavier than the .223/5.56. I weighed a few to illustrate the point: The 115-grain 9mm FMJ weighs 0.444 ounce. The .45 ACP 230-grain FMJ is 0.737 ounce. On the flip side, a 55-grain FMJ 5.56 comes in at 0.407 ounce.

That doesn’t sound like much? Multiple these by 30 to fill a 30-round magazine, and you’re looking at 13.2 ounces for 9mm, 22.11 ounces for .45 ACP and 12.21 ounces for the 5.56. Additionally, most magazines for pistol-caliber ARs hold more than 30 rounds, and the bolt group and buffers are usually heavier as well.

AR-15-For-Home-Defense-Feat
Compared to its pistol-caliber cousins, an AR chambered for 5.56 NATO has a host of advantages.

Is weight really all that important factor? In my opinion, weight is always something to consider. A lighter AR is easier to get on target, easier hold on target for long periods of time and it’s faster when transitioning from one target to another. For competition, self-defense or patrol use, all of these characteristics are important. If circumstances require you to carry the AR for extended periods of time, plus additional magazines — weight becomes important quickly. Remember, the whole purpose behind the development of the intermediate rifle cartridge was weight; the lighter the ammunition, the more you can carry.

Advantages Of A Pistol-Caliber AR

What are the advantages of the AR firing a handgun round? Well, one obvious argument is commonality. You can have an AR that fires the same ammo as your pistol. Some variations go a step further and use pistol magazines. This could be an advantage, but I think it’s small compared to the disadvantages listed above.

Additionally, handgun ammunition is definitely cheaper than rifle ammo. Let’s say you’re a competitive shooter who practices constantly. Your ammo budget will go farther when spent on handgun rounds, whether you’re buying or reloading. Some public and club ranges don’t allow you to shoot rifle-caliber weapons. A handgun caliber AR is the only option you might have, and it’s still good training and practice because the platform is exactly the same as your rifle-caliber weapon. There are also a lot of competitions that are limited to pistol-caliber carbines, so you might be required to use one.

One area where the pistol caliber AR really shines is in the suppressor department. An AR firing sub-sonic handgun rounds with a suppressor is extremely quiet. For me — just keep in mind I’m a little deaf — the sound of the bolt group cycling, ejecting and feeding is louder than the report exiting the suppressor.

Depending on the application, this factor alone might make the handgun-caliber AR the best choice for the job.

Don’t Ever Overlook The Fun Factor

One very important consideration — and I think this is true for all firearm owners — is the fun factor.

Here are two .45 ACP AR-type models built by Flint River Armory. These are fun to shoot, and like all ARs, they’re easy to operate. Handgun-caliber ARs are also an affordable way to send a lot of rounds downrange.
Here are two .45 ACP AR-type models built by Flint River Armory. These are fun to shoot, and like all ARs, they’re easy to operate. Handgun-caliber ARs are also an affordable way to send a lot of rounds downrange.

Shooting, regardless of your ultimate reason, is enjoyable. It’s some of the most fun anyone can have. The AR is easy to operate. Pistol calibers are fun to shoot. With a “handgun-powered” AR, you’ve got both categories covered.

There’s also the “cloning” trend. Several government agencies have used pistol-caliber carbines and sub-guns, and its been employed by different countries around the world. “Cloning,” as referencing the recreation of weapons used by law enforcement and the military, is big and appears to be growing. A 9mm AR might be exactly what you need to complete your collection. Again, that’s not a tactical application, but it definitely falls into the fun category.

Selecting a firearm is a very personal matter. You choose one based on your application, say self-defense.

Maybe you have a specific application that weapon fits exactly — a suppressed weapon or it’s what’s necessary to shoot at your club range. And sometimes, we buy something just because it will be fun to own, shoot and study its history, development and the mechanical aspects of that weapon.

Ultimately, it’s all about what you need … or what you want. Whenever you can satisfy both with one weapon, you’re doing well.

Editor’s Note: This article originally appeared in the September 2018 issue of Gun Digest the Magazine.


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