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Forum Index > Rifles general discussion > .375 _?_ Mauser 98 Oberndorf

.375 _?_ Mauser 98 Oberndorf

05 May 2019
@ 05:53 am (GMT)

JOHN HAYS


Uh-oh. Problem.

I bought this Mauser 98 commercial production rifle at a very, very good price. It was purported to be a .375 H&H modified, from the original .30-06.

Okay, cool. I already have a Winchester Model 70 Safari in 375 H&H, but you can't have too many elephant guns around the house, no?

Although the Mauser shows signs of use, when I put a .375 H&H dummy round in, the bolt just barely fails to lug-lock.

What to do, what to do? Something is wrong here.

I can't sell this Mauser as-is since someone managing to close this bolt on a live H&H round, and fire it, might blow the action up with a pressure spike.

Since it will have to go to a gunsmith for heavy work anyway, I have another option (I think).

Perhaps I can have the barrel set back a bit and re-chamber for .375 RUM? I don't have one of those and if successful it would likely sell for a decent price someday.

I throw this dilemma into the sea of infinite wisdom (a discussion forum) and wait to see what washes back to shore.

Ideas? Comments?






Note the 375 stamped on the custom barrel



Replies

05 May 2019
@ 08:33 am (GMT)

Thomas Kitchen

Re: .375 _?_ Mauser 98 Oberndorf
HI John just to clarify. Are you saying you can't fully close the bolt on a 375 h&h dummy round?
05 May 2019
@ 09:14 am (GMT)

John D. Hays - New Mexico

Re: .375 _?_ Mauser 98 Oberndorf

Yes, Thomas, the bolt moves all the way forward but the bolt handle will not rotate down. Of course with no round in the chamber the bolt closes like glass.

My first thought is that the chamber is a tad too short for a standard 375 H&H case, thus the lugs won’t engage. The dummy rounds cycle quite well through the Winchester.

No barrel obstruction in the Mauser.

It could also be some flaw in the bolt or someone reassembled it incorrectly. I am going to break the bolt down and clean it, but unless it has an obvious maladjustment, perhaps even then, the rifle must go to a gunsmith.

I have no idea the history of this firearm but it probably came from an estate sale. They custom barrel is stamped simply 375 but of course there are other 375 cartridges out there.

If I’m going to get into gunsmithing this Mauser I’m inclined to have it re-chambered —- providing I can do a set-back and still use this very nice-looking barrel.

I don’t really need this rifle but I can’t in good conscious sell a defective firearm to anyone.
05 May 2019
@ 12:46 pm (GMT)

Paul Leverman

Re: .375 _?_ Mauser 98 Oberndorf
Couple of things, John. It's not impossible but it will be a test of your gunsmiths ability to set it back a thread. He has to match the iron sights location perfectly. Before he does this, he should at least cast the chamber. By far easier, and it may answer all your questions. Also, do you have a new case, or a F/L sized case you can try? Maybe it's just a question of shoulder location/angle or of neck length.

Nice looking rifle.
05 May 2019
@ 06:01 pm (GMT)

Thomas Kitchen

Re: .375 _?_ Mauser 98 Oberndorf
now im following you john.

first thing to check is that the bolt face has been opened up to magnum diameter its not some mixed up bolt.

also make sure you feed it from the magazine thousands of people have been caught out with the fact mauser extractors don't like to clip over rims very well.

if the chamber is bit short its nothing to get smith just to run reamer in a touch more but like Paul has said it's probably a good idea to get it cast before you go to far.

also try a full length sized case with no projectile.
06 May 2019
@ 01:29 am (GMT)

Paul Leverman

Re: .375 _?_ Mauser 98 Oberndorf
Right on the money, Thomas. Sometimes the obvious is not so much. The extractor issue is very common, especially with the incredible pressure they employ. Also on the claw is the issue of the angle of the claw, eg, the difference between the M17 and P14. Good call.
06 May 2019
@ 01:47 am (GMT)

Jonathan Kitterman

Re: .375 _?_ Mauser 98 Oberndorf
I would try the correct head space gauges first. That will tell you if it was set correctly as it head spaces off the belt.
You could also try measuring the belt off the dummy cartridge to see if it is in spec or not.

Link to SAAMI drawings, page 131 is 375 H&H.
https://saami.org/wp-content/uploads/2019/02/ANSI-SAAMI-Z299.4-CFR-Approved-2015-12-14-Posting-Copy.pdf
08 May 2019
@ 05:13 pm (GMT)

John D. Hays - New Mexico

Re: .375 _?_ Mauser 98 Oberndorf

Thanks for all the insight. Pretty impressive bunch.

Jonathan, I think you are correct, but I don't have a head space gauge for this. Thank you for the SAAMI specs. I didn't know that file existed and I'm glad to have it.

I do have some spent cases from three manufacturers which I will resize next week when I get my press bolted back on the bench. It will be interesting to see if they pose the same problem as the dummy rounds.

FYI:



I drew a marker line on the extractor as I tried to close the bolt with the dummy round.



And here is the line closed on an empty chamber.

Thomas & Paul, the bolt face is generously sized for this .375 H&H, no hold-off there, and the extractor does lip over. It seems a bit loose to me, not a deep bite, but it works to extract okay. The Winchester M70 has a deeper bite.

Yes, I think it is a pretty rifle, particularly for $190 USD at a pawn shop. Paul, I had not thought about re-aligning the iron sights if I had it set-back and rebored to another .375 cartridge.

I think I will take it over to Charlie Robertson at Score-Hi here in Albuquerque and let him fix it. He is the expert and Thomas is probably right about a touch deeper reaming. I will try those other re-sized spend cases first.

Thanks for your time and expertise and advice.

I will update this post when I get this resolved.

08 May 2019
@ 08:18 pm (GMT)

Warwick Marflitt

Re: .375 _?_ Mauser 98 Oberndorf
John. Just a left field thought...... Has the chamber got the step for the belt on the Magnum case? Its not a Wild cat 375 on a 9.3 case? Or some other exotic custom cartridge setup?
10 May 2019
@ 06:09 am (GMT)

Thomas Kitchen

Re: .375 _?_ Mauser 98 Oberndorf
Hi John
nothing like a puzzle to keep the old cogs in the head moving, its very strange indeed.

the belted magnum head space gauges are based off the the belt so you can cut a belted magnum case down little bit in front of the belt and check it that way.
https://www.brownells.com/gunsmith-tools-supplies/measuring-tools/headspace-gauges/belted-magnum-cartridge-headspace-gauges-prod25180.aspx

Warwick not to sure if you'll see step in the chamber on a mauser or not as it has a double should in the action and no extractor cut out, so the case actually protrudes from the back of the chamber enough to the extractor and bolt to hang onto it.
10 May 2019
@ 03:48 pm (GMT)

John D. Hays - New Mexico

Re: .375 _?_ Mauser 98 Oberndorf

Jonathan, Warwick, Thomas: the .375 H&H sizing dies will not arrive until Monday, but I think this is an interesting point. Is the belt what is holding the dummy round back and causing the bolt not to close?


As Thomas suggested, I cut one of the dummy rounds in half and tried that as an improvised "go gauge".


The bolt closed.


Paul, I have ordered more Cerrosafe to cast the chamber. Now I'm looking around here for the lead casting ladle. I have not done any bullet or sinker casting since the mid-80s.


I have been thinking about this rifle and our discussion for the last few days. I think the conflict is between simply solving the problem by turning it over to Charlie Robertson's shop, or treating this as a learning experience.


The rifle has obviously been used and fired since someone did all the work to convert this Mauser from the original commercial .30-06 to "375". The custom work was of good quality to all appearances, probably from the 1960s. So now I am curious, is it "some other exotic custom cartridge setup" as Warwick suggests? Most likely it is just a short-stroked reaming job, but quien sabe?


This Mauser did not cost me much, and I don't need it as part of my rifle rotation. So for now I will pursue this as a learning experience.


BTW, if I do end up rechambering, what do you all think would be an interesting caliber? I am thinking of .375 RUM? Nathan has good things to say about that one.
10 May 2019
@ 08:43 pm (GMT)

Thomas Kitchen

Re: .375 _?_ Mauser 98 Oberndorf
hi John.
looks like we getting somewhere so it's a belted magnum case.
what dies do you have on hand? 300 win mag or 7mm rem mag?
you could slowly knock shoulder back on brass and see if it will fit.

it could just be tight chamber that needs full size brass, you can stone top of shell holder if need be to make brass slightly shorter.

as for 375 rum its all about feeding and pressure/bolt thrust, if you want bit more thump then 375 H&H then the 375 weatherby could be a good option it did have its origin on mauser to.

11 May 2019
@ 09:58 am (GMT)

John D. Hays - New Mexico

Re: .375 _?_ Mauser 98 Oberndorf

Resized 20 cases of three different manufacturers' .375 H&H cases.

None would allow the bolt to close.
11 May 2019
@ 10:16 am (GMT)

Nathan Foster

Re: .375 _?_ Mauser 98 Oberndorf
Hi John, it looks like it needs to go to Charlie for a visit. It would be good for him to give it a general check over.

Anything could happen with a pawn shop gun. It may even have an entire case stuck in the chamber with the head blown off.

You also need to check the mag box and see if this has been altered. It might not be all that long in there. Check this before it goes away. That way, if the barrel is stuffed, you can think about the likes of the .358 Norma which fits a shorter magazine.
11 May 2019
@ 10:16 am (GMT)

Nathan Foster

Re: .375 _?_ Mauser 98 Oberndorf
Best I spell pawn correctly huh.
11 May 2019
@ 06:00 pm (GMT)

John D. Hays - New Mexico

Re: .375 _?_ Mauser 98 Oberndorf

Yes, Nathan, if you don't want to be pwnd.

Charlie's is where it is going eventually anyway. Even if it suddenly decided to feed standard H&H cartridges, something is not right.


Also, for a "dangerous game" cartridge, I'm not happy that extractor grabs such a small portion of the rim.


Right now Charlie has a couple of rifles of mine that he promises soon, and I have another pair ready to go next.


The Mystery Mauser will have to wait just a bit.
 

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