oldbear, I've had a Freedom arms .454 revolver for about 25 years and used to load for it. I don't recall what dies I used, but never had any issues, even with the FA revolvers precisely reamed chambers. I used AA-9 and 300 grain jacketed bullets. I routinely loaded to about 150 FPS under what the factory 300 grain ammo chronographed. Recoil was still considerably more than .44 Magnum I'd shot and loaded for years.
I just looked up the weight on the Rossi .454. The Rossi .454 with 20" barrel is about a pound lighter than my Henry .357 with 16.5" barrel. If you get around to approaching factory equivalent .454 loads with your Rossi, I wish you well sir: you're a better man than I
