45-70 Case Head Marring

[rr2030]

I load these into my Ruger #1 and upon closing the breech, it creates this mark (see crappy cell phone photos). New Starline cases, mild or heavy loads does not make a difference. Is this normal for this rifle ?

 

[Uncle Ed]

It looks like the breech block has a rough edge around the firing pin hole and its scraping the base of the case.

 

[Dusty Stevens]

^ exactly right. Firing pin hole scraping

 

[rr2030]

I disassembled my No 1. indeed there was a burr, could not see it but I could feel it. Cleaned it up with a Arkansas fine stone. I still feel something, maybe just the edge of the hole? The surface is clean enough now that a razor blade glides over it without snagging.

Looking at the firing pin hole under magnification, I don't see a chamfer, just a square cut hole. So the question is; should this have a chamfer or not ?

 

[DaveTooley]

Pressures aren't high enough for cratering to be a concern but I wouldn't do.

 

[rr2030]

How would the burr get there in the first place. Dry firing ?