So the Rossi is chambered for the 454, it would not be uncommon for there to be some case stretching with a 45 Colt in the chamber, but still be safe to shoot. Look at the reloading manuals or SAAMI site at the dimensions of those 2 cartridges. .2 inches up the case for a measurement point the 454 is speced at .003 inches larger than the Colt then allowing for +/- dimensions I could see another thousandth or more difference.
Like Trouble shooter said Lee makes bulge buster die for removing bulges. full length sizing might also remove the bulge. Downside IMO is reduced case life from working the brass more.
To clarify my Rossi is not chambered in 454. It is 45 colt. They do chamber this rifle in 454 though.