It is chambered for the .45 Colt, also sometimes called the .45 Long Colt. Many will say that it ought to be called simply the ".45 Colt", as there is no ".45 Short Colt". But to distinguish it from the .45 ACP (Automatic Colt Pistol) cartridge and the .45 Schofield, I believe the .45 LC is a good name. I have even seen cartridge boxes from major manufacturers labeled “.45 Long Colt”.
This round was very common, especially after Sam Colt designed the .45 Colt Peacemaker, also known as the Colt Army Revolver. It is said that a cowboy was once asked why he carried a .45. His answer was, "Because Sir, Mr. Colt doesn't make a .46."
It is still a very fine round and can be extremely accurate in a high quality pistol.