ORIGINAL: biscuit jake
The term 45 Long Colt is commonly used, and I have used it myself in conversation. In fact, a revolver for that round is labeled simply 45 Colt.
I've seen old ammo boxes labeled "45 Long Colt". I believe this came into use when the U.S. Army had two 45's in use. They had handguns chambered for the 45 Colt as well as 45 Schofield. Since the Colt round was slightly longer than the Scholfield, the term "Long Colt" became common.