Back when my Dad gave me his WWI vintage S&W Hand Ejector with 6.5" barrel in .455 many years ago I was keen to load for it.
I had also acquired some "Dominion" cases marked .455 Colt. Since back then .455 load data was scarce it was suggested to use load data from the .45 Auto Rim ctg.
I had a set of RCBS .455 dies but since I was going to use 230 gr RN .452" sized bullets which I had on hand [I was also loading .45ACP at the time] I went with my Lee .45ACP dies with the carbide sizer.
Using load data from the Speer #10 manual [first printed in 1979] I went with 6.6 gr of Unique with the 230 gr RN lead bullet in the Dominion .455 Colt marked cases [these are very similar in length to the .45 Auto Rim case]. That data said from a Model 1955 S&W target model with 6.5" barrel in .45ACP/Auto Rim that load combo would produce ~ 787 FPS velocity.
Tried that load combo in the old S&W Hand Ejector with the .455 Colt marked cases with no ill effect, although by the Speer #10 manual, it was listed as the max load for that data. The 452" bullets are undersized for the old Smith as well but from 15 yards on in, the "practical accuracy" was okay. I was doing a lot of 25 & 50 yard target work with the .38 Spl at the time but had no illusions that this old Smith was supposed to be a "target revolver".
It's purpose was as a "side arm" for trench & other close combat work.
Here's the old beast with a Tyler T grip installed to make it more comfortable to shoot with the old small factory grips:
Anyway, the old caveat applies, use caution when using any loading data. Know what you are working with & limitations of all the components: the firearm itself, the brass, powder, primers & bullets.
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NAA.