Posted by on 10/27/2021 to
So are you thinking about a Pistol Caliber AR-15? If you’re not, maybe you should. There are many reasons to have a Pistol Caliber AR-15. Maybe you started off with handguns, got really, really attached to say 9mm and you just want everything to be that way. Maybe you feel that moving from the beefy .45 ACP down to a 5.56 NATO will make you wimpy. You ain’t shooting that wussy, small caliber crap. Maybe, just maybe, you like to have fun and you know how fun shooting a pistol caliber AR-15 actually is.
Whatever your reason there are certain advantages and disadvantages that you inherently get with your pistol caliber AR-15. Here are some:
- Your bullet is generally going to travel slower, but you can use the same ammo for your rifle and your handgun.
- The slower velocity does mean your effective range will be lower, however, it also makes it easier to suppress.
- Pistol ammo does tend to be heavier, this can weigh down your rifle making it harder to aim or hold position, however, your ammo will likely cost less and be easier to find.
- It will likely require modification if you intend to change an existing AR-15 into one, but working on your AR might be a fun project.
And others I’ve probably missed.
Comparing rifle rounds to pistol rounds we can see some notable differences. First of all rifle rounds travel faster and that means more damage, what with all that kinetic energy. They achieve this with higher gunpowder to bullet ratio and aerodynamics. That gunpowder means more propellant for the bullet. Then once the bullet is out of the barrel and in the air its sharp nosed, aerodynamic shape helps it cut through the air. Pistol bullets tend to be bigger and bigger around, so they can create bigger holes.
Why shooting a handgun round out of a rifle is better: With a longer barrel come a few advantages. First, your round will have more velocity, this will make your range longer as the bullet can now travel farther before it starts to drop. You should also be more accurate as you have a longer sight radius for your sights and 4 points of contact keeping you steadier as you take aim. You’ll also feel less recoil due to the greater mass of the rifle.
So if you’re ready to give it a shot and go for it, here are the modifications that can help to change to a 9mm caliber on your AR-15. You’ll need to get a new barrel, to fit the size of the round. Something that goes along with a new barrel is a 9mm sized Muzzle Device. Forgetting to change your muzzle device would to the appropriate size could lead to unpleasant results. This caliber uses a blowback system instead of a gas system, this means you don’t need a gas block or a gas tube. A different Bolt Carrier Group is required, it is heavier since the extra weight helps the blow back system. It also requires a different buffer. You will also need a Magazine Converter, depending on the type you get you can use any 9mm magazine you like, especially the bigger ones.