Cameron
Sorry, I don’t get to spend much time on line lately.
A moon clip is a round disk of spring steel (usually) that has cut outs for the cartridges to snap into. They come in full moon (6 rounds) half moons (3 rounds) and quarter moons (2 rounds, hard to find). The star extractor on a revolver won't work on a rimless cartridge like the .45 ACP without one. I had a 1917 S&W that used moon clips, I wish I still did. Wild West Guns in Alaska does the conversion, as I am sure do others, and is a quality company. They build very nice takedown Marlin 336 customs also.
http://www.wildwestguns.comMy preference is the 336, easy to disassemble and can be cleaned from the breach. Plus side ejection allows for easier optics mounting. I don’t know if the factory chambers for .454 Casull.
Ian