u/Trigunesq

Build list:

Criterion hybrid 14.5 in barrel

Superlative arms AGB

Microbest chrome BCG

BCM recoil mitigation system A5 buffer tube w/ T1 buffer (H2 equivilant 4.5oz)

Shelf on the upper has been modified to avoid binding

Arc fire v2 SS

All tests done with PCM bronze .223 ammo w/ AGB fully open (sometimes in bleed off mode but every test was done mostly with full open). Various mags tested (Pmag, Tmag, Lancer, USGI Stanag)

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I first tried this with a regular ol' push button SS and regular carbine length tube w/ h2 buffer. Ran just fine. Switched to a A5 buffer tube w/ t1 buffer (H2 equivalent at about 4.5oz). Ran great. Nice low RPM. No issues.

Used weights from my old H2 buffer to make my A5 buffer an H3 equivariant by swapping one steel weight for a tungsten. Didnt work out in SS, got one or two shots with a failure to feed bolt over brass. Worked fine in semi. Ok no biggie, the system just doesnt work with that heavy of a buffer weight.

Swapped the buffer back to the original configuration (H2 equivalent). Got an Arc fire v2 and threw it in the gun. One, sometimes two shots (the rare 3 shots) then usually failure to feed (empty chamber or bolt over brass) with a live trigger. Works fine in semi. (Note: I had my original push button SS with me at the range and swapped over to it with the same result, but I didnt realize until I got home that I was still using the standard and not rounded detent so this test can be ignored due to my stupidity).

I can't figure out what the problem might be. My first instinct was that I stupidly put the wrong weights back in the buffer but I double checked (one tungsten and 3 steel) and used a scale and its correct at 4.5oz . My next thought was maybe I should reduce the weight but then I might get bolt bounce and then why did it work amazing the first time?

Anyway, any help or advice is welcome. I want to add that function test (Lower only and attached dry fire) always functioned perfectly. Right now my only course of action I am aware of is to just bring out all my parts and tools out to the range and just swap parts until it works.

I hope I included enough info because it sucks to help someone diagnose a problem and they are vague. I'd be happy to show any pics or any additional info that might be helpful. I'm throwing in a pic of the underside of my BCG that looks like its taken damage. Not sure its relevant because, once again, the gun worked great in current configuration with the only difference being push button safety.

Edit: changed A2 to A5. Its late and my mind is mush.