Okay it’s not a true BCM upper. I put it together with some random parts I had.

Tip to butt:

1) DA Sierra 5 w/ titanium Atlas R adapter 2) Revival Defense/FCD 3P15 3) BCM gas block 4) Expo Arms gas tube 5) Bkings 14.5 barrel (pretty well gassed with a .075 gas port) 6) BCM MCMR 13” FDE 7) Aero upper receiver 8) PSA premium BCG 9) Aero M4E1 lower 10) SSA-E trigger 11) Radian safety 12) Magpul K2 13) BCM MK2 charging handle 14) Aero buffer tube 15) Super 42/H2 buffer 16) BCM stock 17) Sierratac sling

Optics: Arken 1-8 on their mount (still on the fence about this setup)

I’ve had the lower for a few years now but I put this upper together as a general purpose type setup.

The upper runs pretty good suppressed. Only have put around 250ish rounds through it so far, haven’t shot it without a can yet. With my Sierra 5 which is pretty high back pressure I’m getting about 2-2:30 ejection with 5.56 and 3:00 with 223. When I use my YHM R2 I get 3:00 with 5.56 and 3:30-4 with 223. Given this I’d imagine it would shoot very soft without a can. I attribute this to the barrel mainly, I pin gauged the gas port at .075. I believe BCMs is .076 as well as the URGIs.

Hope you enjoyed my little post and write up