How much do you want to change the caliber??
Sometimes nickel will flake off the neck when you change the cal. a bunch, but we've taken 280 nickel brass to to '06 and back after buying/selling guns and it worked fine. Most of my fireforming has been with standard brass though.
You will know right away if it is fine or not. With win 280 brass, it worked fine for me, but I've seen win 7mag brass flake from just trimming it. We've knocked rem 30-06 brass down to 25-06(no- forming-- just necking) and it was fine too.