Will a 6.5/257 AI (40*) clean up a 260 Remington chamber?
I expect so, but thought I should ask the experts.

It should, the .257 case is about 0.2" longer than the .260 case.

It's not the length; it is the fact that it is an AI; otherwise it wouldn't because of the shoulder diameter of the 257 is much smaller than the 260, You would end up with two shoulders.
But with the AI you will be fine.
Just measure the case OD and compare it to the 260 all the way down.

I thought that was the case. I know just enough to get myself into trouble if I don't verify.

Thank you.

Please keep us updated om this project.

I have been shooting the X257 since the late 60s.
Always performed properly if I did my part.

It is just a consideration right now. I have an extra 260 short chambered barrel and I like the idea a lot, but the rub is that I already have a 257 AI. It would be mighty easy to get the ammo mixed up, especially for someone who didn't know better. What I would really like is a 6.5/06, but I dont think that wold clean up the chamber. I am considering the 40* rechamber though.

Im going to do this one. Also known as the 6.5 AAR (All around rifle). Found a good deal on a set of dies, and also some properly headstamped brass.

https://www.huntingtons.com/st....php?productid=20192

https://www.grafs.com/retail/c...duct/productId/73809

I feel like my 260 is a bit on the anemic side. This will be a good fit for an M-48 action.

quote:

Originally posted by TCLouis:
Please keep us updated om this project.

I have been shooting the X257 since the late 60s.
Always performed properly if I did my part.

Have you seen this?

http://www.accuratereloading.com/6.5roberts.html