98 KAR questions

[Ruffasacob]

I'm working on a 98 KAR and it has me stumped. It's an Erfurt dated 1918.
It won't chamber a 8x57 cartridge. I tried to do a chamber cast but the chamber is pitted and I couldn't get the full cast out. So I did a half cast and have the impression of the throat, neck, and shoulder. No broken case or any other visual problem. I have a 8x57 chamber reamer so I checked the pilot in the muzzle. It wouldn't fit. Wondering if it was a J bore I slugged the bore and it miked at .318" So I'm thinking it must be J bore. But the strange part is I pulled a bullet on a 8mm Mauser cartridge and the bolt won't close on it.
A headspace Go gauge will also not let the bolt close.
Any ideas? Did any other country re-work these? I've put the wood back on it and I don't remember if the barrel numbers matched the receiver or not. I need to check that.
Thanks for any insights.
Ruff

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[Calif-Steve]

It sure looks like a correct Kar98a in the photos. Poland had a pile after WWI, but it does not look Polish. Will the chamber accept a 8mm finish reamer? I'm guessing it is a normal 8x57 1918 rifle. Have you taken the handguard off? Is the barrel original? That would be important. Good luck.

[Eaglelord17]

I wonder if it is in something like 8.15x46. Maybe it was converted for civilian use after the Treaty of Versailles (apparently happened to a fair bit of rifles). Apparently it was a popular German civilian round.

[Ruffasacob]

Thanks for postings. The bore won't accept the pilot of new .323" bore 8 x 57 reamer. The slugged bore measures .318", so it's a J bore as opposed to a newer .323" S or spitzer bore. What baffles me is I thought the J bore was changed in 1905 in military rifles to the new pointed spitzer bullets of .323". My gun is dated 1918, well after the change date.
I pulled the wood off again and the barrel number matches the receiver number. I've shown other marks under the action.

Thanks, Ruff

[Eaglelord17]

Apparently the 8.15x46 used a .318 bore. It would also explain why a 8mm Mauser without the bullet isn't able to chamber as it would be roughly 10mm to long. I wouldn't be surprised if it was converted after WWI for civilian shooting.

[Ruffasacob]

Thanks Eagle but I'm not sure I understand. If the barrel matches the gun and was .323" in 1918, how would they shrink the bore to .318"?
If the barrel was mismatched then I could see that as a possibility.

[Calif-Steve]

Not so sure the barrel is original. The serial numbers stampings should be identical. Both stamped side by side in 1918 and done with the same dies. Those numbers were stamped by different dies. Really an odd rifle.

[Ruffasacob]

Agreed, odd.

[Eaglelord17]

It would have been rebarreled, and stamped with the same serial number. Its not like the German Factories just disappeared (well some did, to other countries). As mentioned the font is different. That round was a popular target shooting round up until the end of WWII, and it might have also been a way to keep the rifles when the Treaty of Versaille came into effect (as they were limited on how many rifles could be in the German Militaries possession). Many different rifles have been made up into that round, from Gewehr 98s to single shot Stutizen rifles (I likely butchered the spelling of that).

As you said there is no effective way to shrink a bore and they wouldn't have used a .318 bore from the factory, especially in 1918. Since it won't chamber a 8mm Mauser without the bullet, it has to be smaller. 8.15x46r, is smaller, uses a .318 bore, and was a very popular round in Germany until the end of WWII. We can't be 100% sure of the caliber until you do a chamber cast, or bring it to a gun smith, however given the clues that is most likely what it is.

[Ruffasacob]

Here's a picture of my chamber cast on top and 8.15x46R on the bottom.
8.15 has a much longer neck and a very shallow shoulder angle.
Also using a 98 action for a rimmed cartridge is not ideal, Siamese Mauser not withstanding.
Does anyone know what the mark on the bottom of the barrel is? Small "A" in a circle.
Thanks everyone for your thoughts. Eagle, I do need to make a full chamber cast to better assess the situation.