"Either, Ither, Neither, Neyether, Let's call the whole thing off!" You will get endless arguments on the question. Originally and through the early 20th Century, the term was ".45 Colt" (technically, the gun was, ".45 Colt's Single Action Army Revolver" and the ammo was ".45 Colt's". Where it got confusing was when the ammo was changed slightly by increasing the rim diameter to handle the ejector "star" on the Colt's and S&W guns with the swing-out cylinders. Also, since the Army had quit loading the .45 Colt's when the ".45 Revolver Ball" (today know as .45 Schofield) replaced it, some commercial ammo sellers began advertising the original length ammo as ".45 Long Colt". This was also probably to prevent confusion with the .45 ACP round. Today, most of us refer to the longer cartridge as ".45LC" and everybody knows what we mean.