People talk about rechambering weapons frequently and they usually do so by reaming out the chamber, removing material. I'd like to do the opposite.
I have a messed up Arisaka barrel that's been rechambered for 30-06 and has no collector value. My idea is to take the demilled barrel stub of a 7.62x39 AK rifle, reduce the outer diameter on a lathe, ream the chamber of the Arisaka barrel out, and press the AK chamber into the opened up Arisaka chamber. I understand that this will need to be very precise, as the chamber would have to be pressed in exactly, far enough away so that the bullet seats fully and doesn't get pushed into the rifling upon being chambered but not so far away that it jumps from the chamber to the rifling. I've been told that I would need to resleeve the barrel because "the material transition from AK stub to Arisaka barrel isn't going to line up perfectly and isn't going to be seamless. So your bullet will "catch' slightly there, and best case scenario, it's going to toss your accuracy all to poop". I'd rather not do this and use the original rifling instead.
Has this been done? Can this be done? I will be working with two skilled machinists who know what they're doing and I know how to check headspace. Labor cost is irrelevant.

Here's a mock-up of the placement of the chamber. The end of the colored pencil indicates where the rifling begins in the Arisaka. The barrel won't be going back into the Arisaka, it'll go into an AK.

Interesting idea,  but results are not guaranteed,  and new US AK barrels are very cheap right now.

While I could go out and buy a new AK barrel, I thought this would be a neat experiment. I'll fire the first shots with a string, behind a barrier. Do you or anyone else know of examples of precut chambers inserted into barrels?

7.62x39 is .311, 30-06 is .308.

I would expect accuracy to suffer, if it doesn't keyhole.

You would get a pressure spike, it would be a 310 going down a 308 bore. If it was opposite then it would suffer from accuracy

 

It was probably originally a 7.7 Jap which was a .311(?) bore IIRC.

If you have the skill/skilled help and want to go for it.

I have not checked dimensions, but if you have enough meat left in the Arisaka barrel, I would cut a new 7.62x39 chamber deeply enough to remove the existing 30.06 chamber and trim it to length.  Then turn down the chamber end of the barrel, press a sleeve with an OD to press fit into your AK trunnion over it, pin it, and press the entire thing into the AK trunnion.

I have seen threads by guys on Weapons Guild that have spliced barrels onto barrel stubs as you proposed, but most of those were pistol caliber.  I personally would not try it with a rifle cartridge.

After cutting that off will your final barrel length be over 16", if not you will have to SBR it.

I'm pretty sure that they're won't be enough meat left if I were to try to remove the whole 30-06 chamber.


There will be more than enough barrel left, after all, the Arisaka Type 99 has a 25" barrel.