Give it a rest.
.45 Colt and .45 Long Colt refer to the EXACT SAME CARTRIDGE. It's known, accepted, understood, and yes, even historical.
Do you get all bent out of shape when someone says 9mm Luger instead of 9mm Parabellum?
Or how about when someone has the temerity to say .30-30 instead of .30 Winchester Center Fire?
Many cartridges have multiple correct and/or accepted names, yet it seems that people only get bent out of shape over this one particular cartridge.
Next time someone talks about having a .38 Colt New Police chambered revolver, I expect to see all of the "NO SUCH THING AS A .45 LONG COLT!!!!!" crowd immediately castigate the transgressor with a severe history lesson in how it's correctly the .38 Smith & Wesson...