I have a Rainier MEDCON with mid gas, and an AA XLP mid length piston. I am running the AA low mass carrier and a 1 oz buffer (empty C). Ammo was LC193.
I get spotty reliability and no LRHO on 1/4 open and am running it 1/2 open. I never noticed this before. Only change was going from a C to empty C and adding a Trifecta FS. Recoil does not seem heavy, in fact it is quite light.
Mike