Buffers / Supressors / Backpressure - WTF?
I have 2 SBRs. 1 Colt 6933 bone stock with H buffer - eats anything, any shooting position, any mag, any ammo including my favored training ammo 62 grn Wolf. My other is a (best quality) parts gun with a 10.5 LMT and a carbine buffer and whatever spring comes with the 5 position Vltor buffer tube kit.
Problem - The parts gun with carbine buffer and no supressor shoots and locks back on Wolf ammo for @ 30 rounds when clean and lubed. Then it short strokes and will not strip and feed a live round. Add the supressor - unstoppable - locks back on any mag, yada...
Today I used the 6933 lower with H buffer on the LMT upper - no supressor and yes - more Wolf 62 grn. Runs - feeds, fires, but will not lock back on any of the 3 trusted mags I had. Supressor on - 100%, lock back, yada..
Here is my question I've read about buffers - look at the case rims to see if it is over gased, use the heaviest buffer you can with the bolt still locking back on the last round.... and I think I understand that function is increased with the supressor b/c effectively it is adding gas pressure to the system. What I don't understand is why does it run (but not lock back) with an H buffer and no supressor? Does a heavier buffer delay the opening of the bolt and thus allow additonal dwell time (or gas pressure build up)? Also - WTF with the short stroke / no lock back on the carbine buffer?
Thoughts?
TIA
Also I know many will cry Wolf this, Wolf that - yeah, I know and I get it. That said I've run about 10k rounds of it and save 2 stuck cases it fills the role of cheap training ammo since my goal is more live trigger time for the same dollar. Thank you for your help.