AR 45 Pistol Caliber Carbine Parts

Feb 9, 2019

The AR45: An AR-15 Rifle or Pistol Chambered in the .45ACP Caliber

The AR9 is easily the most popular of the pistol caliber carbines and there’s many reasons for that but the AR 45 is my personal favorite of the PCC platform. For starters I’m a .45 guy, I like the big heavy bullet that is inherently subsonic which lends itself nicely to being suppressed. The .45 caliber bore also means a slightly lighter barrel weight than other calibers.

There are a few considerations when jumping on the .45 AR platform. The first is it’s simply not as common as it’s 9mm AR sibling and that means less options. When it comes to selecting an AR45 you need to decide which magazine style to go with, Glock, H&K USC45 or Olympic Arms. The Glock magazine style is the most common at this time. The Olympic Arms and USC 45 magazines aren’t on the shelves of most local gun shops. The latter are also pretty expensive too. The AR45 never had the same fortune of an inexpensive surplus magazine like the modified UZI 9mm magazines Colt employed.

The 45 AR is blowback design like other pistol caliber AR-15’s. The design requires a special bolt carrier group designed for you magazine platform choice. The recoil system requires a special “Heavy Buffer”. I suggest Slash’s which can be found in posts on this page or in my Olympic Arms .45 AR build project.

These blowback type pistol caliber AR’s can be tough on lower receivers. I strongly suggest KNS Anti-Rotation Pins to hold everything in place. When selecting a trigger don’t buy a light match grade trigger. You need a trigger that can stand up to the blowback design, also make sure the hammer and bolt do not interfere with each other. Remember to also get .45 caliber muzzle device with the thread to match your barrel, 5/8-24 thread is most common but there’s other sizes as well .578x28, M14x.75, M16x1LH. 

Obviously a .45acp chambered barrel is required and there are upper receivers designed specifically for pistol caliber AR-15’s but a milspec model will work as well. Lowers receivers can be purchased designed specifically for the type of magazines you plan on using or you can use a drop in adaptor similar to what is used in the AR9. It should be noted that some fancy shaped lowers will not work with a 45 conversion unit.

MVB Industries AR-15 Pistol Caliber Billet Upper Receiver

The MVB Industries AR-15 Pistol Caliber Billet Stripped Upper Receiver is the perfect platform for building your unique, mission-specific, AR-15 pistol caliber rifle/pistol. Made from a high-strength, 7075 T6 aluminum for durability. Mil-Spec, MIL-A-8625 Type III hardcoat anodized finish adds extra strength and delivers superior abrasion-resistance for rugged field use. Precision-machined to ensure drop-in installation of Mil-Spec aftermarket parts.

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The Foxtrot Mike Products Extra Heavy Pistol Buffer FM-45 has internal Tungsten weights, to improve cycling of any blow-back operated AR-15 .45 pistol caliber carbine action. With its extended length, the FM Extra Heavy Pistol Buffer requires no spacer and helps prevent bolt catch breakage.

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AR15 Carbine Buffer vs AR15 45acp Buffer

AR15 Carbine Buffer vs AR15 45acp Buffer – I like to be very visual in my explanations. One picture truly is worth a thousand words. In the picture above a standard AR15 Carbine Buffer is compared to a Heavy Buffers .45acp buffer. There is probably nobody that understands the AR15, AR10 and 308AR recoil system better than Slash at Heavy Buffers. The Heavy Buffers .45acp buffer at eight and a half ounces is a half ounce heavier than the eight ounce Hahn AR15 Pistol Caliber Carbine Buffer. Slash also recommends a Wolff Spring #16501 for maximum reliability

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