Once you size a 25-06 (or .270) case down to .240 Wby. body diameter, you'll have a "belt", no way around it. Headspace will be on the shoulder, not the belt, anyway.
I agree on the practicality of this exercise. One doesn't blow through a lot of brass with this type rifle, as JB pointed out, and good brass is available, although expensive.
I have re-sized 7mm RM brass into .257 Wby. brass without much problem and was wanting to see how well this one would work. It's harder, IMHO, than the .257 Wby conversion, but can be done.
DF
