I use the RCBS SAA 270gr SWC. It’s a Keith style SWC. I also use even more Lee 255gr RFN, as it’s a 6-cavity mold.
The Uberti Cattleman is a strong revolver, but Ruger ONLY loads aren’t necessary or really desirable.
I dumped my Ruger RedHawk, BlackHawk, and BlackHawk FlatTop. I now have a S&W 625 MountainGun. It will take slightly heavier loads than a SAA Colt, but that’s ENOUGH, really.
Layne Simpson (Handloader Magazine) did an excellent article on Flat-top loads that are also suitable for the S&W, though I stick to his “starting” loads for my S&W.
Basically that means about 1,000fps with a 255gr and 950gr with the 270.
Powder of choice is Hodgdon LongShot.
Other powders are BlueDot and HS6. And, of course Unique.
For 95% of .45Colt usage, the Colt SAA loads are adequate. I use a LOT of either 6.0 RedDot, 7.2gr of GreenDot, 7.8gr of 231, or 8.5gr Unique. Mostly because these are the loads that will maintain case obturation with Magtech brass (thinnest I have ) in my 24”bbl WinM94, so cases don’t get sooty and gas blow back into my face.
From a 24” bbl, these run 1,150fps and 850-900 from a 4-5.5” bbl. They’ll shoot completely front to back, or vice-versa on a 150lb deer. BTDT.
Again, no “need” for Ruger Only loads.
But, 20.0gr of #2400 is superlative if you feel the need for magnum recoil and blast.