You can shoot 45 colt in a 454 chambered RSR ALL DAY! There is no more of a lead issue than shooting a special load in the magnum cylinder of any other caliber/revolver. The
exception is the Casull for the reason that this revolver is a factory work of art, it's tolerances are extremely tight, forcing cone is cut to 11 degrees, there basically is no cylinder gap period, cylinders are line bored, I can go on but the Casull is basically a factory built custom gun as if you sent your ruger to Bowen, Linebraugh, Reeder,etc to have it made into one. Because of such tight specific machined tolerances, there not only show exceptional accuracy but as well can handle extremely higher pressures than 90% of revolvers on the market today. That is the reason they recommend you buy a separate 45 colt cylinder bc of such tight tolerances than can lead up. That is NOT the case with 99.9% of all Rugers made, I own, hunt, shoot and hand load for many for almost 30 years. Rugers tolerances are much sloppier hence why one 4 colt cylinder throats measure .451, .453, .450, etc their cylinder gap are the grand canyon in most cases compared to a Casull. most leading in mass produced commercial handguns like the redhawk is due more as well to the bullets your using and their velocity.
BTW- I love DE's but MANY if not most of the people I know who have bought a 50 have turned around and sold it quickly after showing off a few times. They are extremely heavy, require the correct shooting stance "weaver" per their manual(at least the old one's did), so when brass is ejected you do not have a 50ae fired case branded in you forehead.
, and the ammo is not cheap especially if you do not reload. But they typically do not re sell as fast as a RSR.