Took my new NY State Militia Roller to the range. The firing pin indentation in the primers was very deep on all rounds fired. Since I was testing loads, I used the "standard" 515141 (as cast .5125, sized .512), a .030 veg wad and two different loads and 3 primers - all cases were new Starline. One load was 65 grains (weighed) of KIK 1 1/2, and one was 70 grains (also weighed). Primers used were Remington Large Pistol, Large Rifle and Magnum Rifle. Powder compression was the amount resulting from seating the boolit. Alloy was what was in the Lyman furnace, IIRC about a BHN 11. Didn't test it recently, but a thumbnail will mark it. FWIW, with my old eyes having difficulty seeing the rear sight, I was very pleased with the Magnum Primer/70 grain load.
Is this type of firing pin indentation common on these rifles? My 12.7 Swede doesn't have anywhere near this type of denting. Do I have an excessively long firing pin? I can't see how the pressure could have been high. None of the primers were actually pierced. It was more like the metal flowing around the firing pin (maybe?), but wouldn't that be an indication of high pressure?