AA, that was a particular lot that had about 90% 4.55 head size in them. My poly barrel likes the 4.55's best.
780 fps with the monsters is just how Martin set it up. this is with the HS all the way back flush with the stock. I can tighten the HS and get up to 55 more fps out of it if I need/want to. My rifle shoots the monsters the best with the HS in about 7 turns, which is about 805 - 810 fps. I just keep the HS backed out all the way while practicing so I can get two cards out of one fill. With 7 turns in, I can't get two cards out of a fill.
Beeman, I shoot 5 sighters before I go to the score targets. At this point, I'm pretty sure it's just in my mind. The rifle is fine. Doesn't happen all the time, but often enough for it to be a drag. When it happens shooting in the basement is one thing, in competition, it's another!!