While working on another upper/caliber, I purchased an adjustable gas block from Wilson combat (.750) carbine length. Unfortunately, it would not fit under Mike's Handguard (their on-line lit was not clear). But I liked it because I could adjust if from the front. I'll save it for another day.

Regarding the 80 grain --- my tests were very limited. It is such a long bullet. BUT if you can get it going 3000 fps ---- GREAT.