Advice needed ... bolt opens on firing!

[jmoore]

I've noticed this bolt jump on dry firing, now that I'm reminded

And there's the likely culprit. If the bolt handle touches the socket whilst cocked and the bolt has lots of vertical play, then it's not hard to see how the "unwinding" of the bolt occurs. Pressure from the sear will keep the bolt in it's most upward position until the striker is released. As the pressure is relieved, the bolt moves downward and the hanle, having nowhere else to go, starts rotating. Rearward thust from the cartridge will keep things energetic!

BTW, I assume the 0.015" gap you mentioned is with the striker down and with nothing in the chamber. Since there's no real forward postioning control, the bolt often will move forward until the extractor hits the breech cutout or the LH lug contacts something. Otherwise you might get upwards of 0.060" free motion!

ETA: This reminds me of a thread from 2009-2010, maybe. But I'm thinking that there may be a cure for the vertical slop in the raceway. Need to round up some scrap actions at the shop and do scary things...