Not knocking what your trying to do but if you'll look at 338-06 data it's very efficient and get better expansion out of .338 bullets generally designed for 338 win mag velocity.338-06 is most efficient cartridge period if comparing amount of powder used and killing power plus cheap 30-06 brass used to reform.338 federal is not really any better than 308.

It's definitely worth the expense and time to build a rifle in 338-06 but if you don't reload it's understandable
Again not hijacking but 338-06 is a great cartridge definitely worth looking into