shooting a 7mm Mauser Remington Rolling Block Model 1902

[Reverend Al]

Interesting. Mine may end up seated way out like that, after I get done setting a load. I did an initial test with mine seated, not quite that far out, and it still wasn't touching the lands. It shoots OK Like that?
What's the top round - 300 BLK?

Yes, it actually shoots very well considering that the bore is fairly well worn and the lands are well rounded off on the edges. I shoot either 34.0 grains of IMR3031 or the same of IMR4064 with the 175 grain semi-spitzer bullets seated out at that length and it is typically keeping 5 shots under 3" at 100 yards, and usually with 4 of those in about a 2" group. I always seem to pull at least one wide flyer. (And that is with my fuzzy old eyes and the original open iron sights!)

[Reverend Al]

And yes, the top round is .300 AAC Blackout with a 220 grain round nose bullet seated out for my Remington 700 Blackout carbine.

[atr]

Nice thread,,,
I have a 7x57 model #5 and I have been shooting both cast and jacket successfully for many years. I agree that re-sizing and fire forming GI brass is the better way to go. The black smudge marks on the case you show is most likely a result of the brass not expanding enough to seal the chamber..i.e. a load that is to weak. I always check the cases to make sure that the breach block rolls up tight against the chamber. I have on occasion found that escaping gas will flow back through the firing-pin hole in the breach block so WEAR safety glasses.
I have loaded my 7x57 to 80% of maximum (J's) with no problems. When using cast I tend toward the upper end so that I am assured that the brass will expand enough to seal that chamber.
You rifle looks to be in very good condition. Good luck and good shooting
atr

[EDG]

Safe is good, but still need to be concerned about the angle of that breechblock with having to make up for that much headspace.

All that headspace is probably caused by a too deep chamber.

[brian1]

All that headspace is probably caused by a too deep chamber.

Yes, I think that's what it is. The breechblock still closes fully with the oversize cases, so its angle against the case & barrel should remain the same 90 degrees. I'll keep an eye out for angled heads, though. I haven't done any more on this lately - been busy - but I hope to load up a handful and try them before going ahead and process the whole batch of 50+.
Thanks to all for their advice on this.
brian

[EDG]

A friend of mine had one with a longer shoulder and shorter neck. His first shot pierced the primer. The escaping gas blew the hammer back and the action opened. The primer pocket was blown and the primer was stuck on the end of the firing pin.
The case stayed in the chamber and he was not injured. He expanded his 7x57 brass and formed a new shoulder to fit the chamber and the gun worked fine.