How to convert a .223 AR rifle to PCC /SBR?

[GAgunLAWbooklet]

Ok, I've got an Frankenbuilt AR that's configured as a 20 inch barreled rifle that I use for target shooting out to a few hundred yards.

I would like to use this lower receiver and its fixed M16A1 length buttstock to build an SBR in a pistol caliber cartridge, specifically 40 S&W or 45 ACP.

I would want the barrel to be about 8" and threaded fir a .45 ACP silencer that would itself be about 7" long.

Yeah, I know about the NFA and that I am contemplating a two-stamp configuration weapon.

What parts what I need and where would I order them from to get the kind of weapon I've just described above?

I see the Internet is full of dealers offering to sell handgun-length pistol caliber barreled upper receivers, but they do not mention anything about what magazine system you would use, or how to adapt the magwell of your rifle to accept a pistol / SMG magazine.

 

[GAgunLAWbooklet]

What it looks like now.

I also want to be able to easily (in 10 minutes) put the rifle back into this configuration if I want to shoot at 100 yards or more by putting this barreled upper back on, removing whatever magazine insert or sleeve is in the magwell, and maybe changing out the buffer and spring from inside the stock.

 

[JBWJr]

In, also, for this knowledge...

 

[GAgunLAWbooklet]

Calling all AR experts.

cmshoot

 

[NWSharpshooter]

SHOP STERN DEFENSE - MAGAZINE ADAPTERS - Stern Defense

getstern.com

 

[madcow]

Your best bet would be to find an older Olympic Arms complete upper/mag combo, especially in the calibers you want, they are reliable and just run. If you start building with Foxtrot Mike parts, I heard nothing but issues.

 

[Control for Smilers]

cmmg banshee upper and endo mags.

 

[cmshoot]

I don’t trust the magazine well adapters to go from a full-size magwell to a pistol mag. The exception being the ones for guns like the Colt 9mm SMG, which are pinned in place. Of course, this would negate your ability to swap back to 5.56 quickly.

I would buy a new lower, or a complete gun, that is designed from the get-go to run the magazine of your choice.

 

[GAgunLAWbooklet]

So.....

This stripped AR lower is made specifically for the 45 caliber cartridge, and more specifically the Glock 21 magazine system. $145.

Foxtrot Mike Products .45 ACP AR-15 Lower - Stripped (Non California Compliant)

DetailsBuilding a reliable .45 ACP AR when using Foxtrot Mike Products. The FM Products FM45 .45 ACP lower receiver is machined from a block of billet 7075-T6 aluminum and is compatible with Mil-Spec components. This dedicated .45 ACP AR lower is designed to be used with the highly popular Glock...

www.primaryarms.com

Then, this complete 5" barreled .45 acp
upper, with bolt & charging handle and some muzzle accessory that I don't really understand... is $300.

Would that and some Glock OEM or Pro-Mag substitutes for the Glock 21 pistol magazine be a good way to get started?

I'd probably build it as a pistol first, and if it runs well and I like it, then go ahead and register it as an SBR and have the lower engraved, and put a real buttstock on it.

 

[GAgunLAWbooklet]

And I see ProMag has a 22-round capacity magazine for the Glock model 21 or model 30 pistols in .45 caliber. For $30.
Seems fair.

Fits the Glock® Model 21 / 30 .45 ACP (22) Rd - Black Polymer

We have a huge selection of after market firearm stocks, magazines and accessories all made in our facility in Arizona.

promagindustries.com