Barrel Tenon Adaper/Sleeve

[map55b]

Has anyone experience with taking a "take off barrel", and creating a thread adapter sleeve so that they could use it for a different application? Perhaps turning a Win 70 barrel down to .990x20 and making and adapter to bring it up to 1.1x12.

[B R Shooter]

I wouldn't have a problem doing it for myself, but I wouldn't do it for others. This has actually been done so the barrel could be rotated to see if it would shoot better in a different position. What action has a 1.1" tenon? That's pretty big.

[Ballistics in Scotland]

It should work if done with the sort of dimensions the OP suggests, but I would be wary of doing it with thinner intervening metal, and I would prefer (though this may not be terribly scientific) to avoid having the inner and outer threads of the same pitch. I'd also soft solder the sleeve to barrel thread.

As has been said, not many receiver threads give you as much metal in the barrel as those of 1.1in. The P14 or M1917 Enfields come to mind. If you are adapting an action to a smaller head diameter than it sometimes use, that gives you a bit of leeway. The P14 and M1917 are a case in point, since they use .303 or .30-06 in an action designed for the .528in, head of the P13 experimental round.

Benchresters have proven that you don't normally need a barrel to screw home anywhere near as tightly as is often found in old military rifles. The latter are made to resist great heat, impact, use with the bayonet or rifle grenades, etc. I would want the sleeve to receiver fit to be a very close fit indeed, though, and barrel-to-sleeve as close as I could get solder into. If this is the case, I think failure, which is improbable, would produce hard expansion before it did you any harm.

[HollowPoint]

The project I'm working on now is said to be done this way by those who undertake the re-barreling of these guns. (K31 Swiss Rifles)

For a "Take-Off-Barrel" project it makes sense to me to do it this way. My problems with this method are strictly problems related to my own ignorance about these methods. For example; how much meat or metal do the walls of the actual barrel tenon have to be retained so as not to weaken the chamber for a given caliber? Should the adapter sleeve be made of 4140 CM steel or since it's acting more as a sandwiched/support structure, can it be made from a 1018 or some other steel?

Is it doable? Absolutely; I think you just need to be sure you use the correct materials. In my minds-eye I picture such a "Sleeve/Adapter" as a sandwiched/support structure. As such, it's just a threaded filler used to take up the space between the receiver and the actual barrel tenon. To error on the side of caution would mean we use a metal the equivalent of the barrel itself but, I think that for this application other steel alloys would work.


HollowPoint

[map55b]

Thanks for the input, the sleeve would be made from 4140 or maybe 4140P, but I think the later would be over kill. The Large Ring Mauser is 1.1x12. If I recall the Win 70 is 1x16. The thread depth of the 12 and the 20 together (both sides) ~.23. So I figure if I turn it down to ~.87 and a have a sleeve that is .23, I should be on the mark. I'd "glue" the sleeve to the tenon and while .87 might provide a bit of a thin wall for a belted mag case, I would also have the radial strength of the sleeve and the receiver ring too. I'm not so worried about the sleeve not handling the forward thrust trying to take the barrel off the receiver.

[Blue2]

As BR Shooter noted there are things that we would do for ourselves and feel comfortable with but would not want the liability associated with doing for someone else. As long as I was not going larger than a standard size cartridge like a 308 or 30-06 I have used a 3/4" X 24tpi to do an alteration like this. This is a common thread pitch and it is easy to get taps and threading dies for. You still need access to a metal lath . You could use the old barrel stub if you wanted to. This is how we rebarreled the "Sportco" target rifles that had the locking lugs mating inside the barrel and not on the rifle receiver. We reused the old barrel stub and screwed in a new barrel into the stub. Not a good idea to look at doing a magnum size case this way .

[Cap'n Morgan]

I've seen it done on a few barrels for the Sauer 202 rifle (where the bolt locks directly in the barrel) The conversion is typically done on worn-out Sauer SST 200 (Scandinavian Target Rifle) barrels which can be had for a song. As the stub is rather thin (1.07") the larger magnums are out of the question.


I once matched a Schulz & Larsen barrel with a M 24x1.5 tendon thread to a receiver with a one inch 16 TPI thread (M 25.4x1.58) Basically it was just a reducer bushing with 1" 16 TPI on the outside and 24x1.5 on the inside milled on a CNC to make sure the location of the threads would match inside and out. At places the bushing was no thicker than .012". It worked as planned, but I'll never again do it again. Ever!