There might be different opinions, but mine is that hard primer problem occurs in
Mauser rifles that were supposedly stored cocked so the springs got week from being under tension for 50+ years. Hard primer or not, healthy spring will make the firing pin make the primer go off no matter what. I have however noticed some of Yugo 8mm Mauser ammo fires without a problem and some years will need 2 strikes to fire. I believe , if the spring was strong, hardness of the primer wouldn't matter. I have never experienced hard primers on modern ammo or primers.