Ok, I had to re-register just so I could respond to this thread.
One caveat to my statements....I'm a complete amateur, have little gunsmith experience and am in no way an engineer. I honestly don't how much of what I'm saying is realistic nor if the terms I am using are 100% correct. But I'm completely open to suggestions and/or comments! Now with that said......
A while back I went through this very same question and I too looked and looked then finally found
https://www.24hourcampfire.com/ubbthreads/ubbthreads.php/ubb/showflat/Number/2576875/page/1 and looked some more and, well, you get what I'm saying. My intent was to turn down a Remington 700 barrel and thread then sleeve it for a Savage.
Why would I do this you might ask....
Number one- I'm cheap
Number two- I have more time than money with free access to a lathe
Number three- why not, especially since I couldn't find anyone who had done it or had much information to share
So I look up all sorts of information on thread count, minor diameter, etc... I also try to calculate how much wall thickness I would have between the turned down tenon minus the sleeve (on a .473 case head) and what a factory chambering (full tenon diameter) wall thickness would be on a magnum (.513 case head). After my calculations this is where I say, DO NOT try this on anything larger than a standard .473 case head cartridge. The wall thickness is just too small for anything more than a standard cartridge.
Here is what I would have done if I had gone through with my particular project. I would turn the barrel shank down and thread it to 15/16 (.9375) x24 tpi. I feel comfortable with this size in large part because Browning used to use it on their A-bolt rifles plus I think it would be relatively difficult (again I'm very much a novice) to thread anything more than 24 tpi for all but the most experienced hobbyist. I would leave a shoulder on the barrel to run the sleeve up against and then use some Brownells
http://www.brownells.com/.aspx/pid=645/Product/HOMOGENIZED_SOLDER low-temp 16,000 psi homogenized solder to join the two together. The sleeve material I was looking at was 4140 steel. I found some 4140 pre-hardened 1-1/8" & 1-1/4" on eBay for pretty cheap. My plan was to drill and bore the entire piece, or at least most of it, on the lathe and then cut it into 2" pieces which I could then tap on the milling machine or drill press. Might even be able to tap it by hand but I don't know given the almost 1" thread size. Once tapped I would mill a couple of flats on opposite sides on a far end of the sleeve stub which would be used for tightening the sleeve with a wrench. So at this point we have the barrel tenon turned and threaded, the sleeve tapped and ready to be screwed onto the tenon. Going forward I spread the solder paste on the thread of the tenon and tighten the sleeve up against the shoulder which was left after turning down the tenon. Then you properly heat the joint so the solder flows into each thread properly and after that is done you chuck up the barrel in the lathe and thread for your receiver. You have the strength of the solder and the tension on the threads from being squeezed against the shoulder you created.
An alternate point of view is to just turn down and thread the smallest portion you need then sleeve and re-thread it while leaving the maximum amount of original barrel intact. Maybe a more educated and experienced person could answer that for me?
There are a couple of things I would worry about, first applies to the Mauser. The inner C-ring will receive the torque when the barrel is tightened down. I would worry that torque might loosen the loc-tite or solder the sleeve was attached with. Now you might be able to bevel the sleeve enough so that only the original barrel touches the C-ring but if you turn it down enough you won't have any original barrel left to touch the C-ring. Of course if your tolerances were close enough you could probably just tighten against the receiver face instead.The second is in some of the information I found the length of a turned and threaded joint should be 1.5x the diameter. If you turned the diameter down to 15/16" (.9375) then for optimum strength the length would need to be approximately 1.406".
I might have seriously over complicated my approach. My uncle, who is somewhat of a machinist, wanted to do exactly as you are proposing. I was trying to plan for worst case scenario.
I hope I made sense and explained myself clearly.
BP
