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

Just looked at my brass.  No sign at all of rough extraction but I am getting a faint line on the case 1/4 to 1/3 up from the base and some fresh wear on the sharp front edge of the deflector.  Previous impacts on the deflector were almost to the tip.  Did a 1.9oz weight reduction and changing from a Wilson AccuTac to a SilencerCo trifecta take the gun from just right or even slightly undergassed to overgassed?

MIke

Resolved: http://www.ar15.com/forums/t_2_293/253917_.html&page=1&anc=bottom