Gentlemen, I need some advice,

I have a 1935 Oberndorf Brazilian banner mauser that I want to turn into a 375 H&H. I�ve talked with several prominent and accomplished riflesmiths about the project and have received roughly a 50/50 split in opinions for and against the conversion. My plan is to use Blackburn bottom metal in order to open the action primarily to the rear, and have the riflesmith make the call on heat treating the action.

Several things I�d like to hear about are:

How many of you accomplished riflemen out there have completed this conversion (either hired it out or did the work yourself)?

Speaking from experience, do you recommend the conversion?

Are you satisfied with the results of the conversion?

What would you do differently, if anything?

Whom would you recommend to do the work?

Any replies are welcome.

Thanks
Ibex

First of all, you are wrong about the Blackburn bottom metal. I considered this also for a 375 but when I compared the bottom metal to PM's, I found that Blackburn only takes for the front and not some from the rear. This really takes a lot out of the lower locking lug. I think I am right about this, Jack Belk and I looked over the two of these at the ACGG show in Reno in '03.

Jim

Ibex, a 375 HH on a model 98 has been done thousands of time. Get a gunmaker who has done this a few times before and turn him loose on the project.

I have a 375 HH takeoff barrel from a custom rifle that I will offer to you a very reasonable price. It's a Lilja barrel with a very nice quarter rib, banded sling swivel and banded front sight. It has a removeable muzzle brake with a cap. Send me an email if you have an interest.

Forrest

forrest@bruch.com

Yup. It never seemed to bother the British or Continental gunsmiths. Only recently has it become questionable for some reason.
By the way, you will not be heat treating the bolt/receiver, you would be re-heat treating the bolt/receiver. It is only $100.00, why not just do it? But after the machining and engraving.

Jim is right, Blackburn and Sunny Hill bottom metal extend to the front and require moving the ramp forward. Everyone says to open at the rear but most conversions are at the front of the action. Zastava (Interarms, now Charles Daly)made thousands of Mark X 375s which are opened at the front, never heard of any of those failing, have 2 myself.

Thanks for the comments,

Jim Kobe, I wasn't sure myself so I had called Blackburn and talked to Ted. Maybe I misunderstood him, but when I asked he told me the box was positioned to the rear. I don't have access to one to examine, so I'll have to keep looking.

Re-heat treating. I usually mis-speak, now on the internet I get to mis-type as well.

Any suggestions on riflesmiths?

Thanks
Ibex

This may or may not be cutting hairs, but the Mauser actions should not be "re-heat treated", instead they should be taken down to plumb soft and then brought back up to specs..I got that lecture from D'Arcy Echols one day, and having a good deal of respect for him, thought I would pass that on...

Ted's 375 mag box requires you to take most from the front and just a shave from the rear -- at least that's what it looks like up against my 1909 Argentine.

I looked at several boxes and they all pretty much matched Ted's fore-and-aft dimensions and positions.

Does somebody make one that sits further back?

Thanks,

Just got off the phone with my old smithing teacher from Trinidad. He worked for H&H starting at 14 years and worked for many years in Kenya. His take on this subject was to point out that all the big makers used (when they didn't have a mag length) the standard length Mauser for many BIG cartridges including 416 Rigby and 375 H&H. He does not remember an action blowing up from this extensive modification. Even the ones that were dovetailed across the receiver ring. He did recall a FN that was set back so far it was unservicable. It was opened to 375 H&H and used a 9.3MM barrel. No wonder a .375" bullet produced high pressures. When he worked for H&H he said they opened the standard actions .125" forward and .125 back. Most people he said only opened them in the front. This is his little history lesson!

gunmaker
http://users.elknet.net/chico

I have seen a few 375s on 98 mauser which had set back badly. Some of these were from these fine English and European makers which did it for years with no problems. I have also built 375s on 98s but as time goes on I am less enthusiastic about doing so.
In the end I would have to say, if you are comfortable with it then do so. Just don't remove any more from the front than you absolutely have to.I don't think re-treating of the 1935s is generally necessary unless it has been subjected to enough heat to anneal it for some reason. They are among the finest of 98s IMO.
Some of those I saw which had set back were rifles which had claw mount bases soldered onto the receiver ring and I suspect they were annealed in the process. Another was a factory FN which was just plain soft.
There is no question that the conversion can be and has been done many times. I am, as I said, just a bit less comfortable with it than I used to be. Regards, Bill.

Don,

I heard that London Guns in Santa Barbara, CA makes bottom metal that allows you to take a bit more metal from the back.

Tim

Thanks, Shumb,

I'll check into it.

Bill
I too am not very comfortable about doing this conversion. I have opened many up to 338 Win mag length and never had a problem with doing it. It's too bad the .375/338 was never a factory cartridge. It's a much better fit in a Mauser and a much more efficient cartridge. When I worked for Dakota we used the same overall length receiver for short mag and 375. The 375 feed ramps are very short and steep while the short mags had much more length in the feed ramp making them much easier to feed correctly.

Don
I wonder if the 375 bottom metal from Blackburn is really made for the real magnum length Mauser? After checking my Kuhnhausen book and Lester Womack's "The Commercial MAUSER '98 Sporting Rifle" I learned the distance between the gard screws is the same between the Mag and Std length actions. This means you could take a Rigby bottom metal off a Mag Mauser and put it on your military 98. Not something I would try! Not sure why Mauser kept the same gard screw spacing because it moves the recoil lug back very close to the magazine mortise. This makes the stock very weak on the harder recoiling rifles. Maybe that's why every gunmaker puts an additional recoil lug on the barrel because there's very little support behind the receiver recoil lug. Design flaw?

I'm still not ready to open a std Mauser to 375 length and then sell it to someone else. Maybe if there is, or I fix my CNC and make my own, a 375 floor metal that you have to open the back .125" and the front .125" or so like my teacher said they did at H&H. I'm interested in what others find......

gunmaker
http://users.elknet.net/chico

Why not do a 376 Steyr instead? Opening the bolt face may be the most difficult part of the conversion.

Well, the main reason is that then it wouldn't be a H&H!

There are plenty of great cartridges to fit into a 98, and a 375 is one of them. Of course I am biased because I have the same project in mind too.

A year or two ago someone posted an excellent treatise here on how to best go about opening one up, but I haven't been able to find it yet. If anyone else remembers it a pointer would sure be appreciated.

With the apparent availability of 9.3x64 brass, that would be an excellent choice for an all around rifle. When I had Sterling Davenport build custom rifles on pre-64 model 70 actions the first step is the availability of components. I purchased 200 rounds each of RWS 404 Jeffery and 200 rounds of 9.3x64 RWS brass. This is in my opinion the minimum amount you need for hard to find brass. After the rifles were built, I added to my collection of brass to have a buffer. Now that Norma has 404 brass and Huntingtons has 9.3x64 brass there is no reason not to pursue these great calibers.

Thanks for the replys. I thought I had solved the major problem with the Blackburn bottom metal and box, but I see that my information was incorrect. Again, thanks for the insight, it saved me some money.

If 9.3x64 brass was easier to get I'd go with that cartridge. The fallback choice will be a .338 Win Mag.

I'm still loking for names of talented riflesmiths.

Thanks Again
Ibex

mauser 98's are safe for the .404 & .375 arn't they if they where not people would not attempt .500 jeffery's would they ??

IBEX,
9.3x64 brass is not hard to come by. I just received another 100 pcs from Huntingtons. Not cheap, but not rare either. Horneber is high quality also. I am in the process of doing my second 9.3x64, this time on a pre 64 M70. Danny Pedersen knows I need it for the Nabibian hunt in September. We'll see

Before I undertook my 99,3x64 project, I ordered and received 200 pieces of RWS brass. I then ordered the rifle made by Sterling Davenport and a custom set of Redding dies. The rifle is awsome. Later I ordered 500 more pieces of RWS brass through a member of AR with contacts in Germany. I have enough brass for a lifetime of hunting. I used this same philosophy when I had Davenport build my 404 Jeffery.

why not use that 1935 to make a nice 7 x 57 deer rifle and purchase a winchester .375 like this one already done up and ready to go?

http://www.gunbroker.com/auction/ViewItem.asp?Item=17843921

Blue

Dang, that is one expensive rifle. It didn't specify the maker. Buy it now for $$9000.00$$ I have better for half that price!

Your getting into double prices neally !!

well, how about an original supergrade for quite a bit less.

http://www.gunbroker.com/auction/ViewItem.asp?Item=17918796

A very good friend of mine (lb404) mentioned a good point at lunch today.
If 375 H&H's aren't safe on standard mausers why did Holland and Holland design the cartridge to fit in them! Rigby had an exclusive right at the time to the Magnum length Mausers. Holland and Holland built most or all of them on Std. length actions opened. If you have a Holland & Holland on a magnum mauser it is likely rare and extremely valuable indeed!.......DJ

Guess it is time to put my .02 worth in. I think that if properly done there is no need to worry about this conversion. I think the problem arises when people try to push pressures way above what a Mauser is designed for. If you rebarrel to .300 or .375 H&H, or .404 and keep them loaded to "factory" specs there should be no problem.
Now for those that disagree I will gladly offer to take all the Holland & Holland, Westley Richards, Ribgy, Cogswell and Harrison, Purdey and any other makers who made these rifles off your hands. Just send me your address and I will send a prepaid shipping box and release of liability so that you will no longer have to worry about an "unsafe" rifle I do love both the .300 and .375 H&H cartridges and guess I could force myself to own a couple of nice .404's.......