I have a no name Mauser that was put together in Germeny in the early 1920's, it is marked and proofed for the 10.75x68. I can get it to chamber and the bolt to close on new unloaded brass but it will not close on a RWS factory round. As you turn the bolt handle down it will stop after starting to close about 20-25% of the way down. I colored a cartridge with a marker and it seems to be tight in the neck of the case, no engraving on the bullet.
The gun shows some use so at one time it was fired. The only thing I can think is that I have a very tight chamber or that modern cases are thicker in the neck than they were 80-90 years ago.
What is the easiest fix and who would you recommend I get in touch with?

Get some Cerrosafe from Brownells or Midway and make a chamber casting. Brownells has instructions on the website. You'll end up with a very good representation of the chamber and can make your measurements. If it is the neck, depending on the dimensions the least non-intrusive fix is to neck turn the brass. If you can't or don't want to do that I can on my lathe.

Thanks for the suggestion, but for me, it would make my life simpler to have a more std chamber that factory ammo will run through.
I have several 10.75x68 and trying to keep my brass separated by gun would not be easy for me.....plus I hate to reload if I have any other options.

Might have a .418 bore, with a corresponding chamber. Sort of like the 8mm I vs IS difference.

You might need to have the chamber neck and throat reamed out for standard .423 cartridges, so there is no pressure issue.

I checked, the bore is OK for the std 10.75

Then I would imagine you just need to have the neck and throat reamed out. Somebody must have a reamer, maybe Lothar-Walther.

Why wouldn't you just have the chamber recut with a 10.75x68 reamer? I had a .500 3 1/4" that was too tight and we had it recut with a new reamer and it seemed to help.

quote:

Originally posted by MJines:
Why wouldn't you just have the chamber recut with a 10.75x68 reamer? I had a .500 3 1/4" that was too tight and we had it recut with a new reamer and it seemed to help.

Any suggestion on which gunsmith to ask? I am not having success finding a smith with a reamer on hand.

quote:

Originally posted by Kebco:

quote:

Originally posted by MJines:
Why wouldn't you just have the chamber recut with a 10.75x68 reamer? I had a .500 3 1/4" that was too tight and we had it recut with a new reamer and it seemed to help.

Any suggestion on which gunsmith to ask? I am not having success finding a smith with a reamer on hand.

First find the standard drawings for the chamber and ammo. One or the other is wrong.
Fix the one that is wrong.

My CIP drawing says the chamber at the base of the neck = 11.54 mm dia
at the case mouth = 11.52 mm dia

The max ammo is 11.51 mm dia

Worst case you should have .0004 inches dia clearance. If it is out of round a tiny bit it will not fit.

Check your ammo where the interfence occurs.
If the ammo is larger than .453" it is out of spec. It will still chamber and fire up to about .4533.

This particular cartridge chamber combo does not have much clearance at worst case.

Worst case is the smallest chamber neck and largest ammo neck.

Hi Ken,

I have a Mauser Model B in 10.75x68 with a similar problem. New cases and loaded ammo from a custom ammo maker will not chamber because of the long sloping shoulder, see case on right in attached photo. If you have reloading dies, try loading a round and then fire it and compare the fired case to the RWS ammo. If your rifle has the same problem as mine and you want to ream the chamber, I have a finish reamer and GO, NO-GO and FIELD gauges from Pacific Tool & Gauge Inc you can use. I was planning on having Dave Norin ream the chamber when I had my rifle restored by him but changed my mind. Maybe I’ll build another one someday but in the meantime the reamer is sitting on a shelf.

Jgrabow6493 -- PM sent, very generous offer, thanks

SR4759 -- I will spend some time tomorrow with a mic and see what I have. Thanks for the info.

I have a number of Mauser model B's in 10.75 that I have never shot or even tried to shoot. I guess I will need to drag them out and spend some time seeing if the factory RWS ammo will run through them.

From the CIP data the long sloping shoulder appears to be incorrect.

quote:

Originally posted by Kebco:

I have a number of Mauser model B's in 10.75 that I have never shot or even tried to shoot. I guess I will need to drag them out and spend some time seeing if the factory RWS ammo will run through them.

Just finished checking my Mauser Model B's in 10.75, all of them would chamber the RWS factory ammo and the bolt would close.

Talked to Rube Wells, and the no name mauser will ship off next week for him to touch up the chamber.

Al Stariff competitor pistol to recut your chamber. He can talk you through all the variations. The us spec chamber and dies are WRONG