What's going on here?

[olddav]

I took another look at the casings to see if I missed any pressure signs.... I guess I need new glasses! *Using a magnifying glass I could see ejector marks on about half of the rounds I shot. The seating depth did not seem to figure into it. As I recall all the rounds shot in the morning were fine (cool morning by gulf coast standards) but as the morning warmed up pressure signs began to appear. The last two blew out primers and that's where I stopped, even I could see that as a problem. *So as I stated earlier I am assuming that I was on the edge when I shot my ladder test and when the temp changed (weeks later) the load was too hot. I haven't had a chance to try the next lower node but I'm thinking it will be fine.

[jonbearman]

The first thing I see beyond what I posted is the selection of primer. Winchesters are ok but you would be better off with the cci magnum large rifle primer#250 I believe. They have a thicker cup and with stand more pressure. How is the fit between the firing pin and the bolt head clearance hole for it. Anther thing to look at is the end of the pin with a magnifying glass because you blew so many primers it may very well be pitted up which means you have to change it out or have it polished at the correct contour.

[olddav]

I tried to prime the cases that I thought were ok but all the primer pockets were loose, so in the scrap pile they all go.
Kind of scary when one thinks about it.