I bought this S&W Model 1915 in 455 cal some years ago, bore was very good . I enjoyed
shooting the 455 cartridge but got expensive and unable to reload. Along the way, I found an old FDL rear sight which is easy to install. Also decided to have the cylinder rechambered to the 45 Colt cartridge.
I started using some factory 45 Colt and accuracy was not good, tried black powder reloads and reduced smokeless, still not accurate.
then cut down some 45 Colt cases to the same length as 45 ACP and converted some lead bullets to hollow base. This proved to be the answer.
Also found out later the Cowboy Action Shooter also use a "short" 45 Colt cartridge too