9mm Upper bolt buffer?

[MarinePMI]

I'm new to the 9mm upper assembly game, so I have a quick question.

Does the 9mm (CMMG in this case) upper use the standard M-4 bolt buffer or is there a specific weighted one for the different pressure curve/timing of the 9mm round?

I think I have everything else I need to complete my wife's 9mm AR, but wanted to check with some of the knowledgeable folks here before dragging it (and her) to the range, only to run into potential function issues.

TIA

 

[BLDTYLRY]

You need to get a 9mm specific buffer as they are longer than normal AR15 buffers.

YHM 9mm Buffer Assembly

 

[ORD]

+1 on the above. You should NOT use JUST a standard CAR buffer (whether stock carbine, H, H2, etc.) as they are too short and too light.

Now, you can go with the dedicated 9mm buffer like the one linked above, or you can opt for a specialized pistol-caliber buffer like those from Clint Butler (aka - Slash's Heavy Buffers) like this one here (about 1/2 way down the page...the Model 9Q and 9Q-T depending on your setup, etc.): Heavy Buffers | Products

You can also run a VERY heavy AR-15 carbine type buffer in conjunction with a spacer such as this setup here: Lower Parts - Spike's ST-9BS & ST-T2 Combo (9mm) [SLA0T2C] - $44.95 : Spikes Tactical or just the spacer here: Lower Parts - Spike's ST-9BS Buffer Spacer (9mm) [SLA09BS] - $14.95 : Spikes Tactical If you opt for a spacer and a standard CAR-length buffer, I'd suggest you get at least something in the 4oz and heavier range or you'll start breaking bolt catches and causing yourself issues with lighter buffers in some cases.

 

[MarinePMI]

Thanks for the response guys, I kind of figured there would be a difference. Thanks for confirming that and pointing me in the right direction...

(Disaster avoided...)

 

[blfuller]

Don't forget Slashes Tungsten Heavy buffers.

 

[LRRPF52]

http://www.ar15barrels.com/tech/buffer-construction.jpg