No, same handloads today, Mercator. Same primers. No, no chance these primers are contaminated. They are CCI250 and while this possessed rifle has been sputtering, I have loaded and fired those same primers in other M99 actions without a hitch.
Couldn't see anything wrong. Polished inside the bolt barrel (again), relieved (drilled) a wee bit off the rear end of the firing pin hole in case that was too far back and somehow snagging and then I swapped out the flat washer and the "C" retaining washer on the firing pin so will try that tomorrow if I can get before a snow storm that is due. I am resorting to the old auto mechanic approach - replace parts until it works.
(no offence to our auto mechanic members, but I've been on the receiving end of that procedure a time or two
I am wondering if I might have a cockeyed hole drilled in the end of the bolt; i.e., not truly square and sometimes the firing pin tip binds in there.
Anyway, I've ordered an aftermarket firing pin and spring so will try that when it arrives. Might take the bolt barrel to a machinist, too, and see if he can tell me if it's true.
If all of that fails, I may get out my BFH.