Requested Help Picking parts for AR

[rugmar]

I recently decided to assemble an AR. I decided to do this mostly just for fun and the experience of doing it. I acquired a stripped lower from Anderson manufacturing and recently purchased a lower parts kit by CMMG. I have always liked the look and feel of the fixed A2 style stock so I purchased a complete A2 kit from RRA.

Now that I have all of this assembled I am ready to move on to the upper halve but this is where I need some help. I have a complete SW M&P 15 that I guess would be what most call an M4gery so I wanted this new one to be a little different (as in the fixed stock and the chambering). I'm leaning toward assembling an upper in .300 AAC but not sure what I will need for a buffer. The buffer that came with the A2 kit is a rifle buffer. Will this work? If I need to change it, do I need a different buffer spring? From what I gather the .300 AAC is best in a suppressed upper but I've also seen many carbine length uppers for sale as well. Can anyone steer me in the right direction here.

Intended purpose is the occasional deer hunt and range fun.

Thanks in advance for your thoughts!

 

[SlowFuse]

On the shorter lengths like 7.5" to 12.5" you'll need carbine receiver extension, standard buffer spring and H2 buffer.

16" barrels work best with carbine receiver extension, standard spring and carbine buffer.

If you're wanting to use the A2 I believe you will need a spacer.

 

[Taurus 617 CCW]

You can either go with a carbine length buffer and buffer tube or one of the Vltor A5 buffer systems. It is a compromise between the carbine length and rifle length buffers. It works best with a mid-length gas system but if you plan on shooting suppressed then it should do well there too on a carbine length system. Also if you are going to shoot suppressed you might want to look at the Noveske switchblock. It was designed for suppressors and has three gas settings. Open for standard shooting, constricted for suppressors, and off for single shot suppressed shots with no action noise.

Vltor A5 buffer system: http://www.bravocompanyusa.com/Vltor-A5-Spring-and-Buffer-Kit-p/vltor sp-a5.htm

Noveske switch block: http://www.noveske.com/products/switchblock-clamp-on-5-56mm

 

[Dr.Rob]

I've been running a 16 inch barrel/carbine gas system with an A2 stock and rifle buffer with no issues for years.

 

[MistWolf]

On the shorter lengths like 7.5" to 12.5" you'll need carbine receiver extension, standard buffer spring and H2 buffer.

16" barrels work best with carbine receiver extension, standard spring and carbine buffer.

If you're wanting to use the A2 I believe you will need a spacer.

I ran a 10.5" AR pistol with a rifle RE, buffer and spring with no problems

 

[rugmar]

Thanks for the input, suggestions and links. Very much appreciated!

 

[Ibmikey]

I have a number of 300 Blackout carbines that are set up for supersonic ammunition, 8.50", 12.50", and sevral 16". All of my rifles run just fine with pistol gas on all but one 16" and it uses carbine length gas, there is just no difference in relialibility with supersonic reloads.
I used Faxon barrels on several and a Model 1 sales 8.50" on my pistol simply because it was a gift, surprisingly it shoots quite accurately. Tha 300 has become one of my favorite cartridges and i now have the AR's, Ruger American ranch and the AAC Handi i am holding in the photo that took that hog with a single shot.