Does anyone know what is needed to modify a Mauser 98 action to accept a 375 H&H? I know whats needed for the 458, but I know with an COL of 3.60 the action will need some work. Any suggestions? Thanks.
Jason

You will hear over-and-over not to do this. The action was not made for cartridges this long. Yet it has been done successfully many times. It is more expensive than it's worth to do it right. You really should get a M70 to start with, unless you are a nostalgia buff.

I have done the action work on one Mauser, but I have not put a barrel on it yet. (It may be a while...) So this advice from a rank beginner.

The best advice I can give you is to get one the $400 custom trigger guard/magazines that fits the cartridge, then open the action up to fit. If you can't start with that, then you shouldn't try to play the game. (I did not learn this until 'way too late.)

Hopefully 90% of the metal will be removed from the rear of the action. ( I at least got this part right.)

Get Jerry Kuhnhausen's book on Mausers. Midway has it, as does Brownells. He's an expert, and he'll tell you not to do it.

Good luck,
Don

True indeed, I have heard this, "More money then its worth". "Not practicle"........
But really is any of this about making money? I mean have you ever really come out ahead in restoring an old car? Or a custom Rod? No. The whole thought process behind this is because it can be done. Don you sound like someone that will understand this having opened one up. You at least have had the thought. Anyway The journey is half the fun.

Jason

Jason,

I agree that it's fun and it keeps you busy. I have not given up, although it now appears that I will wind up with a blind magazine and self-reworked military bottom metal, since I opened the action further to the rear than Blackwell or Sunny Hill magazines fit.

I just wanted to see what I could do.

Don

Your project is both possible and feasible,
if you have some metalworking skill and patience. If you don't want to spend $400
on bottom metal you can cut the old mag. box off and fabricate a new one. If you have access to a mig welder and grinder this is not real tough.You can buy the long follower or mill one from bar stock.One thing I learned long ago is to plan on this taking a long time, work slowly especially as you near completion as this is when you are most likely to screw up as you hasten to see the finished product.
I recently cut 2 Mauser actions at different places and welded them to make a short(22Cheetah) and a long(375 Weatherby) The actions are finished but I haven't done anything else.Rifle actions are only pieces of iron and there is no magic to modifying
them into what you want. Good luck with your project.

Jag,

I also asked this question a while ago. The solution I've come up with so far is to use a US Enfield P14 action. There are still a few around, they run about $100.

I was thinking quite hard about doing what 358mark has done, cut two mauser actions and make a matched pair, but decided that should be a project for later. Gun Parts sells a magnum magazine box for the enfields ridiculously cheap, like $8.75 or so. Might want to get that then eyeball it to see how you can get it to fit dimensionally. What sort of mauser action were you planning on using?

Thanks for the suggestions. I will keep you all posted over the course of the project. I have a couple of Mausers that, YES THEY WERE SHIPPED HOME BY A FRIEND (in showing them to the new inlaws some 50+ years ago, stuck the bayonet through the pic window). These are German Mod 98 mausers. Anyway, thanks again.

JAG

Open them up as much as you can in the rear and as little as possible in the front..You can convert a Sunnyhill or get one from Precise that fits the magnum lenth or convert the original magazine preferably a 1909 box...It's really not a complex job..the rail work being the tricky part and you can get someone like Dennis Olson to do that, he is really good and not all that expensive...

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Ray Atkinson

ray@atkinsonhunting.com
atkinsonhunting.com

Thanks for the input. I have opened one up and am well on my way. A smith freind is coming by this weekend to chat and talk about the barrel choice and install. I am not sure which direction I am going to go on the mag, but will decide soon. Thanks again.

I just checked out the Sunny Hill magnum magazine box. The back plate of the magazine is in the standard Mauser location, meaning that to use it you have to do all the opening at the front.

It won't fit mine that is opened to the rear. I think I will go with a blind magazine.

Don

Sounds like you have a plan. Measuring a Mauser action while I write this, I like the idea of opening up the rear of the magazine opening in the action. The 416 Howell I have been thinking about might become a reality. It is what we did with the enfield actions to get the longer cartridges to fit. It doesn't have the same effect on the integrity of the action that cutting it in the front does. Good luck.

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"If you can keep your head about you when all others are loosing theirs and blaiming it on you..."

Don,

Sounds like to me you measured a std., or short mag. box...You are supposed to use a long mag. box and open the action to fit it and widen the rails. With your Sunny hill perhaps it needs to be set back by openning it up and rewelding.

You take all the lenth out in back and less than 75 thousands in front and thats nothing...

Also any magazine can be altered in any direction...lenth or width...

Holland and Holland lenthened and widened standard 98 magazines to drop box and 375 lenth and took only a smidgeon out of the feed ramp, mine is less than 100 thousands..They did excellent work that many US gunsmiths have not figured out to this day simply because they never took the time to study the English guns, or didn't know what they were looking at....

If you want the measurements I will be glad to forward that information to you....Better to get a Precise box that is so designed as I understand it....D'Arcy Echols makes one also but I don't know if he sells them...

These boxes are the reason the old English guns never had a feed problem..Better yet find and old English gun and take it down and study and take the measurments off of it..H&H, Rigby, Westly Richards and a few others.

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Ray Atkinson

ray@atkinsonhunting.com
atkinsonhunting.com

Ray,

I had a Sunny Hill drop bottom 375 length Magnum magazine box in my hands a week ago. It was a beautiful piece of work. The fit of the parts was outstanding. You literally could not see the seam where the trigger guard latch fit into the trigger guard. I sent it back because it didn't fit my modified action, not because of any fault with the workmanship. I had told Andy at Sunny Hill what I was up to before he sent it to me. He was very helpful and friendly, even though he knew there was a good chance it wouldn't fit.

The mag well was 3.615 inches. The rear wall of the magazine box went exactly into the rear slot on an unmodified 1909 Argentine when the screws were started in their threads. To me that means that to use the box you'd have to open the action up solely from the front.

I would not pay $465 for a trigger guard I had to modify to fit my action, though. My 1917 Oberndorf GEW has already been opened to the rear as you describe. I think I had to take .065 off the front ramp - but I may open it up to take 3.66 OAL (right now it's a no-margin 3.65) which would put me right at your .075 number.

I may take you up on the offer of free advice if I start actively working on it again, thanks. Right now I'm too broke to pay attention.

Don

OK, I measured a Sunny HIll and your correct, in that it would have to be modified lenthwise and widthwise to be correct....

The answer to your delima is to buy one from Jim Weisner at Precise or I believe Ted Blackburn..Give them a call, there made right and for that spicific purpose.....be sure and tell them exactly what you are doing...I really like Teds work....

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Ray Atkinson

ray@atkinsonhunting.com
atkinsonhunting.com

I have a standard Interarms Mark X action with an overall length of 8 3/4" I measured the length of the receiver well and found it to be 3.62" You might find it easier to open up one of these as compared to a military action (just a Thought). Kuhnhausen's book mentions that all The Mark X actions used the same overall length action...8 3/4".The difference being the length of the Receiver opening,Magazine well length, and the Feed rails... I have never opened up an action myself so I do not know the procedure. Perhaps someone far more knowledgeable Could post a short discourse on the procedure...I would like to know more about it.
Respectfully
Hans

Ray,

I have already talked to Ted Blackburn, Darcy Echols put me on to Ted about a year ago. I got the impression that Ted made the trigger guards for Darcy when he was still doing Mausers (I may be wrong about that...) Ted was very nice and took time to talk to me at some length. I have not measured his trigger guards, but the chance of my already opened-up action being an exact fit is pretty slim.

Besides that, I really can't afford Ted's work.

Having a blind magazine is no real penalty to me, so I'll just have to keep trying until I make one I like. I used to be pretty good with a TIG, but I'm badly out of practice, and free time is in short supply.

Don

Hans,

If I knew more about it I would tell you, but since I'm just learning, even the following vague description is liable to be bad advice.

I know that opening a Mauser up to the rear leaves a stronger action, but it means that you have to work on the ejector, and bolt stop as well as opening up the bolt face to the magnum dimension and truing it. I welded on a Brownells bolt handle.

The rear bridge gets milled to the FN contour (in height), then the ejection port is increased by moving the opening back to the back of the stripper clip slot in a smooth sweeping curve. It has to be long enough to cleanly eject a full length loaded round. After that the extractor was too short (didn't reach to the rear bridge) so I cut up a broken extractor and welded the back section onto the back section of my good extractor. I used slivers of the old extractor as my welding rod, and kept the front 2/3 cool while I welded it.

The body of the magazine needs to be 1.866 times the diameter of the cartridge (or a couple thousandths less) at the back (base or belt) and at the shoulder. This was worked out by Paul Mauser long ago to get reliable feeding with the shortest stack height. The sides of the magazine need to taper at the top to meet the bottom of the feed rails.

How to open up the feed rails is really an art. I won't be sure I did it right until I get a real barrel on the action. I made some dummy rounds and a dummy chamber (out of oak!), then whittled on the rails very slowly until it fed right. I asked everybody's advice, then sort of filtered it until it made sense to me. If you do it wrong you have a very expensive and funny looking single shot!

HTH,
Don

Don,
Why don't you talk to Jack Belk, he is a world of Mauser information from A thru Z..When I hit a stump I'm on the phone to him and he has the answers..I wish you lived closer, so you could disect my Holland & Holland, blow ones mind, man thoes English and Germans had it down, we havn't even skimmed the surface on Mauser conversions. I used to think I understood the Mauser, I didn't have a clue and I'm not sure I do yet. They are an ingenious piece of art...
Jack posts on HA and perhaps here..If you can't find him, then email me for his telephone number....

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Ray Atkinson

ray@atkinsonhunting.com
atkinsonhunting.com