I'm looking for some help or insight into an issue I'm having with a recent rifle purchase, specifically what appears to be an ultra-tight chamber on a German commercial mauser.
As a way of background, I recently purchased a consecutive pair of H. Barella mauser rifles. I had been casually looking for a pre-war German commercial mauser, and jumped at the chance to bid on a two 1924-vintage H. Barella rifles that popped up on auctionarms. The two guns are consecutively serial numbered, with same dimensions, style, and weight, but in two different calibers - 6.5x54 MS and 7x57 mauser (or at least I think it is 7x57) - two of my favorites. The rifles have seen little use and are pretty minty. Below are a couple of photos of the guns:
I took possession of the guns a couple weeks back. The guns are really beautiful and the workmanship is everything I had hoped for, but like all "new" guns, I was eager to confirm all was well with a trip to the range.
I shot the 6.5x54 first and everything worked as expected, and the gun shot well. When I went to the 7x57, however, I immediately noticed the S&B 7x57 commercial ammunition was difficult to chamber. I had to put a lot of force on the bolt to get it to close. I should have stopped there, but was eager to shoot the gun so I pressed on. The gun fired just fine and the round landed right where it should have, but I couldn't fully raise the bolt handle. Not good.
Back at home, and without a fair amount of force, I was able to eject the spent cartridge. The primer looked fine (not flat), but I did notice some faint scaring on the body of the brass.
I then performed an extra thorough and detailed cleaning of the bolt and and chamber. While the guns cycles beautifully - very smooth and positive the whole time - when I attempted to chamber another S&B 7x57 round, I had the same issue; the round would not chamber and I was not going to force it. I triple-checked the ammunition as well as the markings on the gun to make sure I was not mixing up the guns. As you can see below, the gun is marked 7mm with a "57" under neath it.
My next thought was that I had an ammunition issue. So I tried another brand (Hornady) with the same result, much too tight. I knew it was time to get a cerrosafe cast of the chamber and see what was up.
I just got done measuring the casting. I can provide all the details, but what immediately struck me was the case body width. While the rest of the dimensions are pretty close, the chamber "width" is significantly smaller than the nominal 7x57 body dimensions (0.453" versus 0.472").
So now I am scratching my head. Do the gun's marking not indicate 7x57? Did I (and the seller) make a bad assumption on the caliber? Assuming he marks do indicate 7x57 as expected, why are the dimensions so tight? The gun is pretty minty, and I thought it unlikely to have been modified. But if it had been modified, the dimensions would not have shrunk. So what gives? Did Barella just make his chambers ultra-tight?
I welcome any answers, thoughts, or guesses. I feel like I am missing something obvious here, but I can't figure it out. Thanks.
