I have a 6.5x47 Lapua based on the Small Remington 700 action. One issue with this build is that small rifle primers tend to get pierced and magnum primers were heavily cratered, even on starting loads.
This happens when the gap between the firing pin and firing pin hole is too large, as there is space for the primer to flow into during firing. Primers which are pierced blow a small amount of gas and a small disc of primer metal back through the firing pin hole into the bolt assembly. Not good.
It's possible to remedy this solution by bushing the firing pin hole. This requires the insert of a narrow firing pin hole of diameter 0.062" and to turn down tho OD of the firing pin to 0.060" to produce one thou of clearance either side. The bush also facilitates a sleeve to guide the firing pin through when you pull the trigger.
Needless to say, I now have no more cratering! Neil did a great job fixing this problem and I would highly reccomend him for this work.
Before Bushing
Standard CCI Small Rifle Primers (CCI-400), Pre Bush
Magnum Small Rifle Primers (CCI-450), Post Bush
