ID help with Kettner Sporterized Mauser? Could it be a .318?

[MauserMcGhee]

This old thing is sporterized with a very slim stock, set triggers and claw mount bases (the rings are long gone...it seems to be the end of the world to replace them) On the barrel, "Kettering", "Coln-Suhl" and "8 m/m" are hand engraved along with a Prussian proof mark. Only markings on receiver are the S#, 2.5g G.B.P. and St.m.G. Interested in any info, my main concern is 318/323. Thanks in advance!

 

[Cyrano4747]

If there aren't any barrel markings that state bore diameter the only way to be truly sure is to slug the barrel.

That said, if it's actually a Mauser and not a Gew88 I'd be really surprised if it was in .318.

THAT said, the sky is the limit when it comes to oddball chamberings for sporter guns. For all you know the markings on the gun are totally incorrect and someone converted it to 8mm-06 or something similar years and years back. My rule of thumb is that anything sporterized gets outside confirmation of what it's actually chambered in. Slugged bore at a minimum, but a chamber cast isn't out of question either if I can't figure it out with a few dummy rounds and a bore scope.

 

[Fal Grunt]

The bottom of the barrel will have gauge markings. They will tell you relatively what the bore diameter is, but you will still need to slug it if intending to shoot it.

As Cyrano mentioned, a lot of times these guns can be modified so it is good to double check.

As a good example a friend sent me a earlier 30’s sporter that was chambered in 8.15x46r and clearly marked as such on the barrel. I’d never seen a light weight hunting rifle chambered in that, and it was a very nicely made rifle. Except he said something was wrong with it. Sure enough, someone had reamed the chamber to basically a 308. Whoever did it made a hack job trying to get a rimless case to work. To add to the difficulty the bore slugged something like .300/.315.

 

[ernie8]

Photos would really help . As stated is it a Mauser or a Gew-88 . You need to read some of the old posts on this subject , as it is more complicated than .318 - .323 . As there was never really a .318 [ some rare odd ball civilian ] , much more common is .3168 ish , .3208 and .323 + . To shoot with modern bullets you would need [ depending on the rifle ] .315 ish , .321 , or .323 . A correctly Done and Measured [ and doing that seems to be more of a problem than you would think ] slug will tell all .

 

[MauserMcGhee]

Photos would really help . As stated is it a Mauser or a Gew-88 . You need to read some of the old posts on this subject , as it is more complicated than .318 - .323 . As there was never really a .318 [ some rare odd ball civilian ] , much more common is .3168 ish , .3208 and .323 + . To shoot with modern bullets you would need [ depending on the rifle ] .315 ish , .321 , or .323 . A correctly Done and Measured [ and doing that seems to be more of a problem than you would think ] slug will tell all .

 

[Cyrano4747]

I've got to be honest, based on what has turned up in the other thread you posted about this gun I'd probably take it out of shooter contention. Too rare, not worth risking it. I don't say this lightly, I'm very much a proponent of shooting even valuable rifles.

If it were mine I'd probably cast the chamber to get a definitive answer on what it's chambered in and start the search to find replacement rings and optics to complete it. I might shoot it once or twice once I figured out what it it was in just because I'm incorrigible that way, but it certainly wouldn't be something I shot much at all. And even that would be dependent on really examining the hell out of the stock to make sure it's good to go. It would be a damn shame to crack that lumber.