I recently got a complete .300 blk AR pistol from psa with a 7.5” barrel. I was going to swap out the bcg it came with for a BCM m16 BCG I’ve got at home. I’ve got no experience with ARs with barrels shorter than 16”. Is there any reason the BCM M16 BCG would be less optimized in this short pistol?

Below is all the info I have on the BCG it came with: Full-auto profile bolt carrier group. Shot-peened, mil-spec Carpenter No. 158® steel bolt. Gas Key Hardened to USGI Specifications, Fastened with Grade 8 screws, and Staked Per Mil-Spec.

I recently went and sighted in my AR10 that I built, I noticed that it was ejecting the brass either directly parallel to the ejection port or throwing it waaaaay far behind me. With the research I did it seems I'm undergassed a bit, luckily for me I have an adjustable gas block. Just wanted to ask here (also to try and bring this sub back from the dead) if I'm correct in my assumption, as well as - what the hell direction is opening and closing on the gas block? I'm thinking looking down the barrel at it (unloaded of course) and turning my wrench to the right would close it and vise versa to open it, but I really have no idea. Any help would be appreciated!

Showing off my poverty pony. Been working great. Just got into Multi-gun competition last spring. My wife and I are hooked!