SmallCaliberCentral

First off, you guys, and this website seem to be a wealth of knowledge, thanks for putting this out there for us less fortunate.

Here is my dilemma, I'm trying to figure out if I have a serious problem or not.

Here are my components -
CCI 400
Remington case
H322 powder
Sierra 39 grain Blitzking
C.O.A.L 2.38"

Remington XR-100 rifle

Made up some reloads today for the .204, Sierra says max powder for H322, with a 39 grain pill is 24.2 grs, so I started with some at 23, then 23.4, and lastly some at 23.8.

All of the shells that I shot had a flattened and cratered primer, none of the different loads shows signs of pressure in the brass, and I didn't have any problems extracting the spent case.

I also shot some shells with the same components, except using 26 grains of 4895, and these also came back with the same looking primers.

Should I be concerned??

CCI-400's are quite thin for the 204R. Try CCI-450, Rem 7.5 or similar thick walled primers.
If you can find some Federal 205 Match primers they'll tell you if the rifle is at fault without masking any issues.
They're just thick enough to handle any sane 204R pressures but thin enough to show problems. And darn accurate primers to boot.

Could be just a switch to an appropriate primer will solve the problem.
Could be your firing pin and hole need some work also.

Virgin brass often will flatten the primers due to excessive headspace.
Its the cratering you need to address first.

And it could be that the brass wasn't fire formed to "that" chamber, being shorter than the chamber, when it gets fired, it gets slammed back against the bolt face and the primer may also have backed out a bit.
Check fired brass, see if it will fit back in the chamber, neck size, add new powder and primer and go shooting.