I'm fairly sure it's spring related. I did have 1 light primer strike with my other cz at steel challenge. The guys at the steel competition are saying it's most likely a worn out hammer spring. The cz that fails more often has significantly more rounds through it.
I bought a new extending firing pin, firing pin spring and hammer spring. I'll throw those in there and report back.
All that different ammo and they all have hard primers? I dont think so. If they shoot fine in single action then there is something wrong with that gun. Did you try it in any other guns?