Typical pistol primers will start to flatten at about 20~30k psi, dependant upon manufacturer and magnum as opposed to common. Looking at a 9mm can run as high as 35k psi for usual hundreds and up to 38,500 psi for 9mm +P, there is no question . For an illustration https://winchester-primers-for-sa41159.blogunok.com/32070514/rumored-buzz-on-federal-primers-gm210m