Will a 338 RUM reamer clean out a 338 WSM chamber?

[sambo3006]

I recently purchased a very nice low round count barrel in 338 WSM and would like to have it rechambered to 338 RUM. No big deal if it has to be set back but wondering if a 338 RUM reamer would clean out the 338 WSM chamber with minimal setback?
Thanks!
Sam

 

[Kevin Cram]

According to PTG book of chamber prints.

The 338-300 WSM at the rear of the cartridge is .5586" and .200" forward of that is .5563"

The 338 Ultra Mag at the rear is .5532" and .200" forward of that it's .551"

The WSM is a .0054" larger diameter than the 338 Ultra Mag. You'd need to have it set back enough to clean this diameter up. My advice would be to cut the threads off and start from there, you'll only loose about 1" of barrel.

 

[MontanaRifleman]

Or do a 338 Lapua...

 

[sambo3006]

The WSM is a .0054" larger diameter than the 338 Ultra Mag.

Dang it, I knew that but I forgot. No big deal. The Lapua is an intriguing option. I'd have to have the bolt face opened a little. Hmmm.