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Mauser 98 in 458 SOCOM

mechanist

Plastic
Joined
Jan 30, 2009
Location
Richmond & Davis, Ca.
Hello:

I'm contemplating a new project, and at this time I'm just at the beginning of the design phase. I've decided to post this because I think that it's a good idea, and I'd like to share it with others who might be interested in building a similar rifle. I haven't created any working plans yet, and I'm just at the conceptual level for this project. Because I will need to complete other projects that I've got in progress prior to beginning work on this, it will most likely be next summer before I can start cutting metal for this rifle.
Right now the only thing that I have to offer is just the idea. Your input is welcome, and if you find this inspirational, then you are more than welcome to step ahead of me and attempt a similar project. If you do, please share any insights that you incur with others at this forum, so that we can all benefit from your experiences.
Like a lot of people, I've always wanted a bolt action rifle in 45-70. If you feel that the 45-70 is better suited to lever actions, single shot falling or rolling blocks, and that the use of this cartridge in a bolt action makes no sense to you whatsoever, then your are completely normal, and have an abundance of practicality. Only those eccentric tinkerers, or nonconformist shooters, who like a challenge would find this appealing.
There are only really four options available to anyone who would like to undertake this type of project: Either convert a Siamese Mauser, a P14 Enfield, a Lee-Enfield, or design and build your own custom rifle. The problem with this for me is that, even though I very much like Mauser's, the Siamese Mauser isn't exactly what I'm looking for. The P14 Enfield is becoming as rare as hen's teeth. And I know that I'm going to take the heat for publically saying this but, I never did like the Lee-Enfield very much. (I'm sure it's a wonderful rifle, it's just not my cup of tea.)
What I would want is a Model 98 Mauser in 45-70 caliber. If your a knowledgeable gunsmith, you can fill a voluminous book with all the reasons that this is not going to happen. It can be done, and would only cost all of the riches of Karnack to accomplish, but would still only be a dicey proposition. The lynch pin in this equation is that darned rimmed casing, and all the alterations that would be required to accommodate it. The Mauser 98 was designed to work with a rimless case. You would be required to make so many modifications to the action to get this round to function, that designing and building your own rifle from scratch would start to seem more plausible.
Then I had an idea. Actually it was one idea that lead to another. First, why not build a 98 Mauser in 458 SOCOM? Other people have built rifles in 458S on both the Remington 700 and the Savage 110 actions. Why not the Mauser? The 458S duplicates the ballistics of the 45-70, but in a rimless case with a standard size case head. Because of this, there is no reason to alter the bolt in the Mauser in any way! The standard bolt and extractor will work.
You could turn and chamber your own .458 barrel blank. The only problem that you'd have to overcome is reshaping the rails and magazine opening so that the cartridge will feed properly. This is where I started thinking about my second idea for this project.
With the Mauser's integral magazine, there would only be room for two rounds, (the 458S is a fatty!). Because of the controlled round feeding, this means that you would only have one in the snout and one in the mag. On top of this, the 458S is a short round, and you would have to add a spacer block into the back of the magazine well, and use a short follower. All this would be after the tedium of file, fit, & retry in getting the contour of the magazine opening just right.
Then it occurred to me that you wouldn't have to do any of this. All of the heavy work has already been done for you! You see this rather ingenious fellow who invented the 458 SOCOM named Marty ter Weeme, designed it so that it would work right out of an unaltered M16/AR-15 magazine. You don't need to hand fit a Mauser magazine to feed the 458S cartridge. All you need to do is modify the Model 98 to accept the detachable magazine from an M16.
To see if this could be done, I made up a 3D drawing of a M98 trigger guard and a generic drawing of a 10 round M16 magazine in Autodesk Inventor. With some creative cutting, jigging and welding it looks like the M16 mag. could be made to fit. Though I haven't made up any mechanical drawings to verify it yet, it looks like the spacer block that I would need to machine to go behind the M16 mag. could accommodate the magazine release mechanism from an M16 as well.
This would be a very sweet conversion, and both a fun build as well as a capable hunting gun. I don't see the need to go with a conversion to one of the 458 rounds based on a belted magnum case. 458S is a low pressure round that is well below the safety margin for even a small ring Mauser. The 45-70 already carries a punch like a freight train loaded with sledgehammers, and the 458 SOCOM is its modern equivalent. If you would like to build something in a bolt action that duplicates the 45-70 in power, this would be a good choice. If you want a 458 that approaches magnum velocities, then this is not for you.
Personally I'm looking for a hunting rifle that would perform well with both cast and jacketed bullets. This rifle would have all the power and range that I'd need for hunting costal blacktail deer and feral pigs. A ten round M16 magazine would be legal even in hippie occupied California, and would hold 3 rounds of 458S. The 458S was designed to be used in a 16 inch barrel, but with a 20 inch barrel on a bolt action, I might be able to use slower powders, and get more versatility.
I've already set aside a M1938 Turkish Mauser to be the Frankenstein's guinea pig for this experiment. Like too many amateur gunsmiths, my paper thin wallet doesn't match up to my boundless enthusiasm, so it will be at least six months before I can start work on this project, and probably a year before its done. If it works out well, I may build another more refined version on a VZ-24 later. Once I start work on this rifle, I'll post some of the ongoing results. If you find this to be an interesting idea, and would like to build a similar project, by all means give it a try.

Mark

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Maybe use .450 Marlin since it is a factory cartridge. Turn off the belt and rebate the rim (to .308 size) if those things offend you and you could use the bolt without modification.
 
Mark,

Thing 1: If you really love the 45-70 it may be possible to to make a bolt from scratch. Just a thought. I just hate to see someone give up on a dream.

Thing 2: Making a bolt action is not as hard as many make it out to be. I recently fired the prototype of a bolt action that I designed from paper. It would handle a 45-70 (or any other cartridge you could legally own and would want to fire from your shoulder... It can be done.

Thing 3: If the Turkish Mauser with an AR mag is the way you want to go... Think it through. There will be some welding to do and the steel in some of the Mausers gets damn hard when welded. Could make for problems in later operations if not considered up front.
 
Hi GGaskill & MIBill:

Thank you for your suggestions and input. First on the 450 Marlin; its a good round, but rather than modify that cartridge to fit, I could just buy 458 SOCOM brass ready to use from either Starline or Midway for about the same cost as 45-70 brass. It's a good suggestion though, and if the 458S hadn't been invented, a modified 450 Marlin would've been the way to go.
As far as the 45-70 in a bolt gun, I haven't given up on a dream, I just think that this is a better way. I've owned and shot a 45-70 in a 1874 Sharps replica for years,(until I gave that rifle to my idiot brother), and liked the round a lot. I just think that for a more modern hunting rifle this conversion would be a better idea. As for machining my own receiver, I like the idea of designing and machining a bolt action from scratch, and I plan on doing that in the future. I think that it's great that you've done this, and I understand the skills and craftsmanship that are required to make such a build - my hats off! The first designs that I plan on building though will have the bolt face for the 0.378" dia. case head, for cartridges based on the 223 Remington/5.56 NATO case. I've already got at least two rifles to build before I can get that project, so its just on my mental back burner right now.
The idea that I have for converting the 98 Mauser only requires welding on the trigger guard and magazine assembly, not on the receiver. I'm confident in my TIG welding and metalurgical skills. I've worked on some rather amazing stuff that would make a magazine well seem not so difficult. I actually gave this aspect of the potential built some thought after I came up with the M16 magazine idea, and determined that there would be three ways to do it: 1. Cut the forward ends of the magazine sides, bend them out, and weld in spacers. 2. Machine a jig to hold the trigger guard in position, cut away the magazine portion, then bend up and weld in a custom magazine box. or 3. machine up an entirely new trigger group with the custom sized magazine well. Of the three options I like number 2 the best.
Again, thank you for your input, I value your opinions.

Mark
 
I'm almost done with a bit more odd but similar conversion. SSK industries brought out a cartridge called the American Eagle. It uses the 50 cal action express case and the only modification is to rebate the rims to fit a 308 bolt face. You load surplus 750 grain 50 BMG projo's and the overall length fits in a standard Rem 700 action. The cartridge was developed for maximum effect at sunsonic speeds. I built a 700 and had fun with it but it functioned as a single shot because of the cartridge diameter.

I was playing with a Schmidt Rubin (1899 style)and slipped a round in the magazine. It stacks and feeds perfectly without modification and the bolt face fits the cartridge perfectly. I finished the barrel last weekend and as soon as i get it blued I'll proof it. The round is not high pressure. The velocity is about 1100 fps with a 750 grain bullet. It's virtually silent with a can and hits like a runaway truck.

It's a cheap and technically simple conversion and no one else has one!
 
Hi All:

While doing research for this project I found out that the magazine conversion that I was planning already exists. ATI makes a detachable magazine conversion kit. I found this item at a place called Legacy Sports International. I've decided not to try to re-invent the wheel, when you can just buy one right off the shelf.

Mark
 
You might want to rethink your objection to the Siamese Mauser if you can find one now. They were routinely converted to 45-70. I have one that has been converted to use a slightly shortened 460 Weatherby Mag that has been blown out to 50 cal.
John L
 
Don't knock doing a 45-70 in a Mauser. I have a Siamese Mauser that I made up into a 45-70 and I think the only real issue is the magazine box. I you can find Siamese bottom metal with it's sloping mag walls you're pretty much done. Or really jump in with both feet and convert a stock bottom metal by cutting down all corners bending to right angle angle and welding in heavy sheet metal in the resultant holes.
 








 
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