NY State Militia Roller Question

[Ed in North Texas]

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?

[singleshotman]

Almost all of the old timers have large firing pins, most of them are .125 dia or bigger.This is due to the fact that large(.250) berdan primers were used untill 1880 or so, when the present type primer was adapted by Winchester.Most of the others followed suit in a hurry, as it was much easier to reload.Your load is not high pressure, but perhaps your bullet is a little small, most of these 50-70's used .515 dia bullets.Lyman changed the cherry to .512dia some years ago to suit Shiloh Sharps rifles,but did not change the number.I a lucky enough to own an early mould which casts .515, these were designed for use in Trapdoor springfields.

[bigted]

in my experience the preassure sign that is among the first is a cratered primer...is this what you have? another thought is that your block may have an enlarged firing pin hole and the primers are flowing a bit in and around the pin into the enlarged pin hole.

just a couple thoughts and i agree that the black powder is not likely to create preassure problems. if the primer dent is very deep... [ i wouldnt want to chance a ruptured primer that close to your face ]... you may need to grind a bit on your pin or bush the hole with a smaller pin diameter for the small end of it and build another smaller pin for the bushed smaller block hole.

just some ramblings from the peanut gallery

[NickSS]

Most old us made single shots in 50-70 were designed to shoot the old us army standard ammo which was a copper shell with an inside primer. The shell was relatively weak compared to modern brass but it was fairly thick over the primer (the head looks like a RF case but is really a CF). Due to this, the hammer springs and length of firing pin is a bit long and gives a really stout blow to the primer generally leaving a deep dent in the primer and some times piercing it. I had to stone a couple springfield and RB firing pins to stop piersed primers. As long as the primers are not piersed I would do nothing to the gun.

[Ed in North Texas]

Thanks all. I suspected the answer Nick gave was what was happening, as the Swede doesn't have the same symptom (the Swede 12.7s are converted from rimfire to centerfire with a Berdan primer). But better to ask. No pierced primers, not even the pistol primers.

As for the size boolit, it shoots well. I posted a picture of a 7 round (my youngest son took care of most of the rest I had loaded) group on the Single shot forum under a NY State RB post. Given that I can't really see the rear sight, I'm happy with that 50 yard group.