I use .45 Long Colt because that is the traditional name for it. Although SAAMI says it is just .45 Colt. Most people know exactly what I mean when I say .45 LC, but may not know that .45 Colt means the revolver cartridge while .45ACP, oops, make that .45 Auto is for automatics.
Yes, I know there have been quite a few revolvers chambered for the .45ACP cartridge.
Now the reason I don’t say 9mm Luger long is because that is a made up name.
I’m not sure where they started the .45 Long Colt nonsense since I have a Sear’s and Roebucks catalogue from 1900 that lists it as .45 Colt.
Save yourself some typing.