Ha ha. Sorry, didn't mean to steal your sign off
You're right, I failed to explain my point clearly (in fact it was partly wrong)
(Updated my original post to say) what I meant to say was that there is more to it than just resizing necks. You can't just grab any other brass bang it through a die and voilà.
As per 30-06 example, significant trimming is required to shorten the case.
As per comment about the base potentially being difference, you can't turn 30-30 brass into .308 despite both being a .30 cal brass of about the same length.
Soz for any mis-information Ade. Made sense in my head but didn't come out right as words
Be Safer. (Yeeeah, in your face!)