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Best buffer for AAC 9"

Posted: Wed Jun 01, 2011 10:32 pm
by drozdws6
So I'm finishing up my 300 BLK build and needed some help on what buffer to use. My AAC 762SDN-6 is still several month down the road. So I need a buffer that going to function well with supersonic rounds. I am running the AAC 9" blackout barrel. Also I planned on loading up some 110gr.-125gr. rounds if this matters.

Thanks

Re: Best buffer for AAC 9"

Posted: Wed Jun 01, 2011 11:45 pm
by JasonAAC
drozdws6 wrote:So I'm finishing up my 300 BLK build and needed some help on what buffer to use. My AAC 762SDN-6 is still several month down the road. So I need a buffer that going to function well with supersonic rounds. I am running the AAC 9" blackout barrel. Also I planned on loading up some 110gr.-125gr. rounds if this matters.

Thanks
Our 9" uppers are setup to run with H2 buffers. that's where i'd start with yours.

Re: Best buffer for AAC 9"

Posted: Thu Jun 02, 2011 8:07 am
by 300Blk
Yes, H2.

And our 16 inch uppers are best with H buffers.

Re: Best buffer for AAC 9"

Posted: Thu Jun 02, 2011 9:46 am
by NordicG3K
I was already running a Spike's ST-T2 heavy buffer in my registered lower and when I used my 9" Blackout upper it wouldn't lock the bolt back on an empty mag. Going to a regular carbine buffer it now runs fine, but the only load I've put through it so far is a 147gn FMJ over 15.5gns of H110 which may be a bit on the light side.

Re: Best buffer for AAC 9"

Posted: Thu Jun 02, 2011 11:31 am
by 300Blk
NordicG3K wrote:I was already running a Spike's ST-T2 heavy buffer in my registered lower and when I used my 9" Blackout upper it wouldn't lock the bolt back on an empty mag. Going to a regular carbine buffer it now runs fine, but the only load I've put through it so far is a 147gn FMJ over 15.5gns of H110 which may be a bit on the light side.
That is a very light load. I would look into 2-3 more grains of powder.

130 grams is the weight of an H2 buffer.

http://www.silencertalk.com/forum/viewtopic.php?t=42479

Re: Best buffer for AAC 9"

Posted: Thu Jun 02, 2011 5:13 pm
by imyomama
NordicG3K wrote:I was already running a Spike's ST-T2 heavy buffer in my registered lower and when I used my 9" Blackout upper it wouldn't lock the bolt back on an empty mag. Going to a regular carbine buffer it now runs fine, but the only load I've put through it so far is a 147gn FMJ over 15.5gns of H110 which may be a bit on the light side.

got exact same buffer setup on my 9" ar blk .. and no problems from either 125's to 220 smk subs ... i'd say it's your load

http://www.youtube.com/watch?v=2UehOw94yc0

Re: Best buffer for AAC 9"

Posted: Thu Jun 02, 2011 5:32 pm
by 300Blk
I should also add that the AAC 9 inch is also designed to work with the HK-416 buffer, which is powdered Tungsten. I am not sure if the Spikes is as heavy though - but should be close enough.

Re: Best buffer for AAC 9"

Posted: Thu Jun 02, 2011 9:27 pm
by Tom12.7
I'm not surprised about the different buffer weights from different manufacturers. I have a H2 buffer that weighs in about halfway between my Colt H and Colt H2 buffers. I bet it's a CMT. What are the identifying marks on the CMT?
Thanks,
Tom

Re: Best buffer for AAC 9"

Posted: Thu Jun 02, 2011 11:37 pm
by NordicG3K
The Spike's buffer also uses powdered tungsten and weighs 4.3 ozs (122 grams). I use the same buffer in another lower for my 12.5" 6.5 Grendel and it works great.

Thanks for the input on my load. I had a feeling it was light. I started out real low and increased gradually until it was ejecting and feeding fine. The only issue was locking open on an empty mag. I've started playing with the 110gn V-Max and I'll have to try the Spike's buffer again.