BCM 20" upper buffer question...

AR/M4 AR Technical Discussion
1

I am putting a 20" BCM upper on my S&W carbine lower. Basically I am wondering if I will need a different buffer than the original S&W carbine buffer. My bolt group is also a BCM. Thanks, Plumber

2

I didn’t have any issues running mine with both a standard carbine buffer and an H buffer.

3

Give it a try and if you have issues get a heavier buffer.

4

A standard carbine buffer should work. I don’t have a BCM 20" but it has worked fine with a CMMG 20" 1/7. I doubt that the BCM would have a larger gas port.