Flattened primers and reading pressure - rifle handloads

[tominboise]

I have a 22-250 that flattens primers with my handloads.  No cratering or other pressure signs like sticky extraction, etc.  The primers are Winchester standard rifle primers.  Winchester factory loads also flatten the same amount, that is, they look the same as my handloads.  Are Winchesters softer then other primers, or is it a quirk of my rifle.  The load is 39.5 gr H380 under a 55 gr PSP.  This is from .5 to 2.0 gr under max, depending on which book you are looking at.

Any opinions?

[josebd]

what kind of rifle?

[tominboise]

Tikka M595 varmint rifle.

[josebd]

well im no expert but i would change maybe powder and primers

[KN]

Reading flattened primers is something of an old wives tale that won't go away. By the time a flattened primer tells you that preasure is too high you have already surpassed a slug of other signs. Some you already listed such as sticky extraction, split casses, cratered primers,etc. If you are within the load book specs with your loads, you are far from telling anything from a flat primer. Primers will flatten as the round is fired. First thing that happens after preasure builds inside the case is that the primer backs out of the hole slightly untill it hits the bolt face. Then as preasure increases the case is pushed back untill it hits the bolt face and the primer is pushed back into the hole flush with the end of the case. Being hammered like that it naturally flatens out in the process. That is why alot of primers that are seated a few thousandths of an inch below the face of the case always come out flush after firing. I forget which gun mag I read all this but I think it was Rick Jamison.    KN

[Old Syko]

What KN said with one addition.  Yes, Win. primer cups are softer than say, CCI.