I’ve got a BCM recce midlength that I’m trying to get set up to be as reliable as I can since it’ll be my main gun and used for carbine classes.
I’ve just recently completed the gun so I’ve only put a small number of rounds through it so far (100 or so)…right now I’ve got just the standard carbine buffer.
Are there any reliability gains to be made by putting an H (or H2 or Spikes heavy buffer) buffer in my gun? I know you can get felt recoil reduction with the heavier buffers but my top priority is reliability so if the regular carbine buffer makes a midlength run best I’ll happily give up any recoil reduction.
Just looking for opinions and I know there are a lot of smart folks here.
An H works fine and would be what I’d use if I were primarily shooting 5.56mm NATO pressure ammo. (H=3.8oz).
If shooting .223 pressure ammo I’d use a CAR weight buffer (3.0oz)
A CAR 3.0oz buffer will have less muzzle rise due to the faster cyclic rate and lower moving mass. In all 3 of my BCM midlengths I use CAR buffers. 2 are strictly competition rifles, 1 is a multi use: training, defensive and 3gun rifle.
I asked Grant this very question several months ago. He recommended I stay with the H Buffer, but to ultimately replace the buffer spring with a chrome silicon version. My impression was BCM4’s really are GTG out of the box. 
well the majority of my shooting is done with .223 so it sounds like I should probably stick with the standard CAR buffer.
As far as the chrome silicone buffer spring, who sells those…sounds like a worthy upgrade that shouldn’t cost too much.
If I switched to a chrome silicon spring would I have to potentially get a different weight buffer to compensate for any difference or is the spring weight the same as a stock one?
I bought this spring for my BCM4: http://www.gandrtactical.com/cgi-bin/commerce.cgi?preadd=action&key=25006&reference=/cgi-bin/commerce.cgi%3Fsearch%3Daction%26keywords%3Dbuffer%26searchstart%3D0%26template%3DPDGCommTemplates/FullNav/SearchResult.html
I’d leave the buffer alone. I don’t think you have to be in a hurry to replace the buffer spring, but when you do ultimately replace it, use a CS spring.
I really don’t think there is a lot you can do to make a BCM4 better than it was when it left BCM.