450Bushmaster.net

Was sizing once fired factory cases and had this happen, decapping pin punched the center out of the primer.

New one for me in almost 40yrs of reloading.

Had this happen to me a few times in my years of reloading. Usually happens with a tight primer pocket or a sealer was used. Manufacturing problem. If it ammo you bought send it to quality control. If not take an awl and tap it down the side of the primer to fold it in and pry it out. You will have to use a primer pocket reamer to size the hole then the new primer will fit properly. I use the feel of how the primers come out as to when I ream all the primer pockets on those cases or not.