45-70 loading question

[JagerDog]

ya..cratering by itself isn't neccesarily a sign of high pressure. If coupled with flattened primers then it is.

[SFCRangerDoc]

Does the firing pin fit too loosely in the bolt face allowing a lot of room around it for the primer to flow into the space?

OH, quite possible. The IAB Sharps copy isnt the 'greatest' copy of a sharps ever and the firing pin hole is kinda large. It actually shreds off brass shavings from the primers when I drop the breech. I was thinking about taking a fine file to the edges to smooth them out but the firing pin hole is definitely on the large size. Other than that the primers dont seem to be flattened out. I'll try to post a pic of the firing pin area tonight.

[SFCRangerDoc]

Sorry guys, it took me longer to get a couple pix. Heres 2 photos of the breech block and the firing pin pressed so its at full extension. It does appear theres quite a bit of gap between it and the hole...

[pacrat]

And Bingo.

There is your primer flow issue. If you are happy with the lower pressure loads. You don't really have to do anything to it. I would advise against using Federal primers. Don't know about now, but they used to be softer than CCI or WW.

If you want to start bumping pressure for higher performance/velocity such as hard hitting hunting loads. You can have the breech face "bushed" to closely fit the pin. Which will stop the crater/flowing.

JM2c

[XxWoodsHunterxX]

If they are for your Sharps you can have a lot of fun with cast bullets. On the longer heavier bullets I drop a bullet into the chamber then using my calipers to check the distance from bullet base to where the cartridge rim will sit, this is my OAL or how deep I seat the bullet into the case. I hope this makes sense. I do use Swiss 1.5 Fg
Cruise missiles from a few years back.

Those look like my 500gr Travis Frick .458s.

[bfoosh006]

BTW... remember Remington 405gr .458 bullets are stepped profile... so do not substitute that load data for other 400ish gr bullets.

You can see it in the first photo... they are a narrower profile towards the tip, then the rest of the shank / bearing surface.