I have a pair of 25-5s/.45 Colt from the '70s. A .452 ball slides through, hesitating in some of the chambers. A .454 does not go through. I am no bullseye shooter, but it hits as accurately as I can aim it.
If you like the cartridge you'll love the gun, methinks. I handload everything from Cowboy loads to hunting loads. You can really tailor a load to suit you.