Don't forget, the .454 SRH - including the Alaskan - can also chamber and shoot the shorter still cased .45 Schoffield rounds, too. Good luck on finding them, too, but a few smaller sources still make them. Their rim is 'normal' sized - ie, larger than the dimunitive one on a .45 Colt. I had my .45 Colt Redhawk's ejector star skip over the rims and jam easily - don't recall that happening more than once with my SRH (Never with .454's!). Let gravity help - eject with the muzzle up.
An important caveat re .45 Colts and a .454 - always clean the chambers well before inserting .454 Casulls. Anything, like the carbon/lead residue from shorter cased .45 Colts, that slows down the crimp release or impedes the bullet movement in the very high pressure .454 Casull round's operation can result in a dangerous pressure spike. It's fun to launch rounds at over twice the max .44 Magnum KE level - and still want to do it again... and again! Eventually, you get older... my SRH was ultimately traded in on a new .357M - to launch .38's with... my wimpification!
Stainz