I've got a fairly new Bushmaster 20" Hvy bbl. A couple of weeks ago I was at the range working on finding my "one hole load". However I first tried some 55g, some 60g, and some 75g Hornady TAP loads to see how they would shoot. When I got to the fifth round of the 75 grainers, something didn't sound quite right, and the empty only flew out about 12 inches onto the table. The bottom part of the case looks like its a belted magnum. The primer blew out and you can tell the cartridge base got hammered pretty good by the bolt face. When the rifle cycled on that round I never noticed any difference. It wasn't a slam fire. I was shooting slowly for groups so I know that wasn't the problem. It almost looks like the bolt didn't close and lock, but if it didn't, would your trigger group work like normal? Anyway, anyone have any ideas what happened? It's worked fine since with no problems. Thanks Greg

No, they were Hornady TAP 75 grainers

I'm sure the bolt was closed. If the bolt doesn't close the firing pin can't hit the primer.

It was a high pressure load, for whatever reason.