Re: difference in primers?
Generally, I don't see much of a difference , if any, in accuracy between the Cci and Federal magnum primers in accuracy. I have experienced differences in ES when changing primers. I have more frequently seen differences using standard primers in my 308 when changing brands. Overall, I'd say it's a crap shoot and the only way to find out with your specific load is test the different primer. I'm doing this right now with my 308 target rifle. This component shortage is murder.
"Let us speak courteously, deal fairly, and keep ourselves armed and ready"-T. Roosevelt