I sat down to prep and prime some .300 WSM cases. I have reloaded for other rounds but these are the first in the .300 WSM for me.
They are Federal once fired cases.
I use almost exclusively Federal primers. Due to the shortages I bought what I could find on the shelf and that is the Winchester large rifle magnum primers.
I got the cases sized, pockets cleaned, trimmed, deburred and chamfered.
I cleaned the primer pockets with a hand held Lee primer pocket cleaner.
I went to seat the primer using the Lee Auto-Prime XR and it seemed like there was no resistance. I took the case out of the shellholder and the primer fell out of the pocket. I tried a few more with the same result. I tried a different package of primers but they were undersized as well.
I just primed a bunch of .30-06 cases using the last of my Federal large rifle primers using the same lee tool and they had good feel and primed just fine. I also cleaned those primer pockets using the same Lee hand held tool.
I measured the primers and they seemed to be around Ø.210" while the pocket on the .300 WSM seems to be Ø.219".
It would seem to me that the primer pocket is oversized.
Are the primers undersized or are the primer pockets oversized?
I have never had to use undue pressure to seat a primer. I assume I am not supposed to press them in hard enough to deform the cup to hold them in.
Anyone ever run into this situation?
Is there any way to "shrink" the primer pocket?
Should I just order new brass? I have read that maybe Federal brass is prone to having oversized pockets. Is this true?