RCBS BULLET MOULD .45-255-SWC 424 and the design tweaked version RCBS .45-270-SAA 424 are supposed to be very good bullets. I might buy one of these after a little more research.
I don’t know if a SWC will feed smoothly into a Win M73 rifle. I can’t imagine they’ll just drop into the chambers of my Ruger New Vaquero’s without snagging on the chamber edge.
My only experience with a SWC design bullet is with some commercial cast for 357 Mag.
The SWC lip that is responsible for cutting nice clean holes in the target paper gave me fits trying to load them into the cylinder of S&W 686. That paper cutting lip would snag on the chamber edge every time whether I loaded singly or jiggled 6 in a speed loader.
Lesson learned from loading my 357, for my 45 Colt cartridges I prefer to cast a smooth feeding RNFP, I don’t care that they tear a ragged hole in the paper target.