Identifying this Mauser and the cartridge it takes

[eshift]

S&S stamp ( Sauer and Sohn)

 

[MontanaGrant]

Chamber cast sounds true.

This is a stupid question but I have to ask: Is it rifled all the way to the end?

I’ve seen a number of rifles that have been counterbored, possibly due to muzzle damage. Then the bore is larger than the rifling back for an inch or so.

 

[Ericedwinbates]

Probably 9x57. Had a similar issue. Was able to chamber 8x57 brass but not 9.3x57. I slugged the barrel using soft lead fishing weight. Measured .356= 9mm.

 

[SkullKeeper]

Chamber cast sounds true.

This is a stupid question but I have to ask: Is it rifled all the way to the end?

I’ve seen a number of rifles that have been counterbored, possibly due to muzzle damage. Then the bore is larger than the rifling back for an inch or so.

Yes sir, it’s rifled to the end. I didn’t realize they did what you described - interesting fact.

 

[cmk]

It is very difficult to judge a rifle based only on photos. The proof-marks seem to be German. N under a crown means that the rifle is Nitro proofed. 7,9 mm is the designation for a barrel caliber 8mm/323. However, the stated relatively weak proof-load of 2,75g powder suggests a weaker cartridge than the 8x57IS. The magazine length fits a cartridge with a 57mm case. Since the diameter of the barrel is rather .358 than .323 and taking into account the reduced proof-load, it is quite possible that it was a rifle initially caliber 8x57IS rebored to caliber 9x57.

My guess is that this rifle started life as an 8x57I, rather than the 8x57IS. That is the old pre-WWI Patrone 88 with a .318 bore rather than the modern .323. It worked at a lower pressure, and was proofed with a 2.75g load of smokeless powder (according to wikipedia at least).

Patrone 88 - Wikipedia

en.wikipedia.org

That would also explain why somebody went through the trouble of re-boring it. .318 bullets and ammunition are a lot harder to find, and the 8x57I caliber is rather obsolete.

What it is now is anybody's guess until you get a chamber cast.