Whats the story on flat primers?

[scottishkat]

While doing barrel break in I shot some federal and winchester factory loads. I noticed the primers were brass colored. They flatten out completely compared to my cci 250 primers. Should I look for flat primers at all when looking for pressure signs and just keep giong until I get a sticky bolt or ejector mark? I have never loaded past the flat primer condition cause that was what I was taught. I cant decide if factory primers are just weaker than cci or if factory loads are hotter than what I load.
Any input would help. Thanks.

I have not seen any hard data based on primers flattened there is plenty of info out there on primer brisance ratings.

This relates to the actual cup of the primer and some being manufactured softer than others. Federal primers a have a low brisance rating and therefore in some cases have not been deemed suitable for use in semi auto's. Winchesters are higher. The CCI BR2 is in the middle. Not sure about the 250 but it is a magnum primer.

If you are noticing flattened primers there are plenty of causes. Back in the day it was something my father taught me to observe. I still do however my experience indicates as others have stated that it is generally not cause for alarm especially with the federal 210M. Did you check the load in the factory rounds is it compressed etc?

In any case research primer brisance and you should find some interesting info on primer cup construction. If you want to take this further you really need to know the velocity of your loaded rounds.

Good luck and shoot straight.

Bob