Good evening all you pistol heads. Hope you've all enjoyed a sunny bank holiday.

My friend passed me his CP88 over the weekend as hes been having issue with intermittent discharge when the hammer is released. Its hit or miss whether is actually pops the valve or not. Having taken it down check through the only thing I can see that might potentially cause this issue is the level of wear on the hammer, theres quite a dimple worn in it, and possibly the firing pin being slightly shorter than new from years of use. I'm thinking the combination would mean the hammer cannot strike the pin enough to open the valve consistently. Just wondering if anyone has seen this sort of behaviour before? And does anyone know the overall length of the firing pin from new, currently measures 7.54mm?