Small Thread Magnum?

[roscoedoh]

In my limited research, I find that most recommend against rebarreling to a magnum caliber in a small ring thread M98. And I have to wonder why? Particularly if one were to take the added expense of having the action properly gas carburized. And I'm not limiting this thought to Turks - there are also G33's, G33/40's, etc - there were many variation of small ring thread M98s made throughout the years.

 

My thinking here is that if you can buy a commercial rifle in a common short magnum, like a 7 Rem mag or .300 Win Mag, who's barrel thread OD is less than .980", why then would a properly threaded SR barrel not provide enough "meat" to house a Magnum in a SR thread Mauser? Mausers are reputed to have about the best gas handling ability of any known action and again, if one were to have the action properly carburized, where's the beef with building a magnum?

 

 

[Sailormilan2]

Roscoe, this was cussed and discussed at the old forum some time back. The opinions voiced against it cited the large, deep Mauser Whitsworth style threads. In my opinion, those against seemed to think that if the Mauser had the shallower newer commercial style threads it might be more feasble. I may be mistating their opinions, but if I do, it is unintentional, so please correct me.

Barrel steel is supposed to be harder than receiver steel. If I remember one argument correctly, it was: Which was better........... less of the harder barrel steel and more of the thougher, ductable receiver steel or more of the barrel steel and less receiver steel?

[roscoedoh]

Interesting.

 

However, if the threads are cut to correspond to the receiver properly and form a good joint, they should act like a solid unit. And with a Turk at least, the overall outer receiver ring is the same size as the standard large ring Mauser that we build everything on. It should be just as strong in my mind.

 

I guess the question becomes: does the extra .120" in receiver thread size make that big a difference? If I remember correctly, that is the difference between large and small ring thread size.

 

Also, I'll say that from what I read, barrels are softer than barrels - at least most of the time. That's why Ackley could blow the barrel off an Arisaka, screw a new on in, and keep plugging along. Or at least, this is what I read somewhere. I may be wrong too.

 

[donmarkey]

Also it's the method of threading, most people cut a relief cut in the barrel instead of cutting off the first thread in the receiver. That weakens the barrel, not a problem with large rings but could be with high pressures and small rings.

-Don

[carzngunz]

First, which commercial receivers are threaded for .980" or smaller od threads? I don't have too many commercial rifles but I do have a couple of Turks and this has interested me for a while now.

If other rifles have their magnum chambers machined into a barrel that is basically .900" (.980"- .083" for the threads), then doing the same on a Mauser should be no problem. My only concern has always been that with the effective barrel diameter at about .900" and the largest case diameter of say a 300 Win Mag at about .513" that only leaves less than .200" of material around the chamber. 60,000psi chamber pressures and that small amount of metal doesn't give me a warm enough feeling to want to put my face behind the bolt. It may be perfectly safe but I don't have any proof either way.

 

I would like to build a magnum chambered rifle on one of my Turks but I think I will need some more input before I take that chance.

 

Second, the threaded joint won't ever be as strong as a solid piece of steel of the same size. It's just not possible to get that kind of fit and still be able to screw the parts together, not to mention the incredibly accurate machining that would be necessary to get the threads to mate up that close.

[Guest Guest_albertashooter_*]

I am fairly sure that the Browning BBR used 15/16 (.9375) x20 threads on the barrel shank and I have not heard of any blowing up.I know several older smiths who have told me that the chambered Turks for Magnums all the time in the years gone by and never had a problem. However they all said they had discontinued the practice as current thinking discouraged the idea.

I personally would stick to .470 base size cartridges in turks as it probably is not worth the risk.You only have one face and two eyes and cannot replace them easily.

[ken98k]

Has anyone ever opened up a LR small barrel shank reciever to large shank dimensions?

[roscoedoh]

What got me thinking about this entire concept was a barrel I saw at the gunsmith's shop who did my parkerizing. He had a nice stainless steel 7 Rem mag barrel that he claimed to have taken off a Browning A-Bolt. On the off chance I could get it rethreaded I asked him to measure it - smaller than .980" OD. And the chamber walls looked pretty thin now that I think about it. Still, this got the little wheels turning upstairs...

 

I wanted to field this idea to see what others were thinking. It sounds to me like there are too many other actions to work with, but I still had to ask...

 

Thanks all for the feedback.

 

Jason

[albertashooter]

I do not know if this would help anyone, but there is a way to use a smaller shanked barrel in a standard large ring Mauser. What you need to do is make a bushing that is threaded on the inside to fit the barrel and threded on the outside to fit the action and is locktited or epoxyed in place. The difference in thread size would have to be great enough that the bushing has some structural integrity. I have never done this but saw a posting by Bill Leepers where he stated that he had dome this many times without a problem. The post was regarding using a Remington barrel and Bill recommended turning the barrel shank to 15/16 by 20, I am guessing to have a bit of meat in the bushing. Bill has forgotten more about Mausers than most of us know and I would no problem in following in any of his reccommendations. I would however restict myself to standard cartridges same as a turk.

[Jimro]

Well, let us sit back and do a "thought experiment".

 

Imagine a 300 Win Mag chamber in a Turk action, and the stresses caused by powder ignition. Physics and chemistry tell us that the pressure inside the brass is equal at every surface, but that the strength of those surfaces is different depending on the thickness of the brass. The brass is thickest where the steel would be thinnest, but let us consider the scenario of total case failure.

 

Will, 0.200 inches of steel hold back 60,000 psi? Or would it expand slightly and gain strength from the reciever ring? I am not an engineer so I do not have the skill set to solve such a problem, but I'm sure several folks here can and will solve it.

 

Anyways, I've seen what happened to a MarkX 7mm Rem Mag after it was loaded with a 308 Win cartrige. I'm amazed that it fired, but it seems to me that a total case failure would probably resemble the aftermath of such an explosion. The stock was completely shattered down it's length, but the rifle saved the life and eyes of the shooter.

 

My guess, just sitting here and visualizing the process in my head, is that a Turk would handle a catastrophic event with the same aplomb as a regular large ring action, and be just as wrecked as a regular large ring. If the stresses of repeated firiring did cause the chamber to expand slightly in some area then the chamber would just be slightly larger, which means a little more work for full length resizing. Since there is less steel this would happen quicker on a small shank barrel than a large shank barrel, but it would still happen on the large shank barrel.

 

So all in all it seems to me that if you went ahead and got the action gas carbeurized to prevent lug setback, and rethreaded a barrel for small ring, that you could have a serviceable magnum rifle that would give you a lifetime of shooting.

 

Now, would I do it? Probably not, I'm not much of a fan of high pressure magnums, they have their place, but they don't offer enough advantage to really make it worth it for me. I am a recoil wimp.

 

Jimro

[ken98k]

Let me re-frase my last question.

I believe a G-33 is a small ring / small barrel shank, therefore doesn't apply to this question.

A K-Kale is a large ring, small barrel shank. After truing the face of a K-Kale, the only difference between it and a v-z24 or gew 98 is the thread diameter.

Can this be opened up safely?

Not that I have the technical skills or equipment to do it, just something thats been on my mind for awhile.

[Jimro]

In theory yes, you could open up a K.Kale turk to large shank dimensions safely, and it would be darn near identical to other standard m98's except for the different steel, very tough but not very hard.

 

Jimro

[Clark]

I am looking at a Win 70 mag barrel with .939" minor thread diameter and a Turk barrel .886"

If the mag chamber is .513", then the difference between the Win 70 and the Turk would be .213" thick barrel wall vs .1865"

 

At 86,400 psi proof load for the 300WM, if the case head separated and let all the pressure the chamber walls, but did not leak gas, the chamber could see stress in the barrel steel using the thin wall formula:

S = Pressure * Inside Diameter /[ 2 * wall thickness]

S = 86.4 kpsi * .513" / [2* .213" ] = 104 ksi [Win 70]

S = 86.4 kpsi * .513" / [2* .1865" ] = 119 ksi [Turk]

 

How would one know that the barrel went to yeild?

The threads would fit better.

 

It does not scare me.

If I can get the Turk to feed, I will make a number of them.

I don't think my threads COULD fit any better:)

[Jimro]

You know Clark, we've been considering the .531 inch base diameter of a magnum cartrige, but that is the diameter of the belt, the diameter of the body of the case just in front of the rim should be closer to .506 (I just measured a random 7mm Rem Mag shell) , which would change calculations slightly.

 

After all, commercial double cut C ring actions do not support the left side of the case head at all, instead relying on the gas handling ability of the m98 action to save the shooter in case of total case failure, just like that MarkX that I saw.

 

So the more I think about it, the more reasonable a Turk magnum seems. Except that I am still a recoil wimp.

 

Jimro

[Clark]

 

So the more I think about it, the more reasonable a Turk magnum seems.  Except that I am still a recoil wimp.

 

Jimro

9251[/snapback]

 

I have a 9.5 pound Ruger #1 in 7mm mag with hard rubber butt that really kicks.

I have an 8.5 pound VZ24 in 300 Win mag with Limbsaver butt pad that is a pussy cat.

 

Nice butts give an improved sensation.

 

[carzngunz]

I did not realize that there were modern actions that used barrels threaded that small. This being the case I wouldn't think there would be any problems using the Turk.

 

Like Jimro I am not into recoil, but I would like to have a 300 or a 338 just say I have one.

 

I'm also on your side Clark, I am all into improved sensations!

[carzngunz]

I ran across this a little while ago searching for other material.

 

http://www.riflebarrels.com/articles/custo..._700_action.htm

 

 

Although they are talking about a larger case, 378 Weatherby, 416 Rigby, the chamber wall thickness is the same as our small ring Mauser magnum. Mr. Lilja seems to have some concerns of his own as to the chamber wall thickness being approximately 0.200".

 

Just thought I would pass this on.