I have some RWS Berdan type primers. They're hard. They work fine in my milsurps but I get unacceptable velocity deviations in a couple of commercial sporters I've shot that ammo through. One is a Husqvarna chambered for the 8x57.
I haven't had any failure to fire issues or indications of hang fires, but there's still what appears to be a consistent ignition issue, that isn't there in the milsurps.