I've been handloading nearly forty years and have done some stupid things but never have experienced a pressure excursion until last friday. At least I think that's what it was.
I had been shooting the 154 gr. Hornady IB in my 7mm STW with WW brass, F215GM primers, RL-25, starting @ 79 gr. and going up to 82gr. Pressures seemed ok with all of these but accuracy wasn't what I wanted. Keeping all other components the same, I switched to the Barnes TSX 160 gr. FB and cut my starting load to 77 gr. I'm seated well off the lands and cases are trimmed to within specs. My first shot with the Barnes TSX gave me a stiff bolt lift, shiny ejector mark and blown primer. I packed it up and went home to check my data and codgitate. I'm still puzzled. This load should have been mild. I was shooting over a chronograph and the load clocked 3171 fps @ 15 ft. from the muzzle.
"Fenced yards ain't hole cards and like as not never will be, reason for rhymers and old five and dimers like me."