You'll notice on post #2 or #3, the thickness of CCI SRP, are the same as the rem 6 1/2, and CCI specifically calls out, not 223, but AR rifles.
A PRIMER ON PRIMERS
So apparently cup thickness isn't the issue with .223, per se it's dangerously too thin. Rather, you can't run it as high a pressure or in an AR. As per usual reloading best practice, start low and work your way up, and you'll be fine.
A PRIMER ON PRIMERS
So apparently cup thickness isn't the issue with .223, per se it's dangerously too thin. Rather, you can't run it as high a pressure or in an AR. As per usual reloading best practice, start low and work your way up, and you'll be fine.