Moonclips are unnecessary for a "laid back" competition like the one shown on the You Tube clip above. You will have a lot of time to reload between target arrays. Therefore, I recommend using Safariland Comp III speedloaders which (after a bit of practice) are almost as fast as moonclips. Plus you won't have to fiddle with special tools to load and unload the rimmed .38 special or 357 magnum rounds from your moonclips. (It can be a PITA. I shot a moonclipped GP-100 in USPA revolver for a couple of years and I know.)
don't get me wrong, I love moonclips in my SW 625 with .45 acp rounds.)
All you will need are some Comp III speedloaders, a reloading block, and some speedloader holders. Besides, you will then be set up for IDPA Stock Service Revolver matches. (For IDPA,,you will need some kind of cover garment - a cheap fishing or photographer's vest will suffice.)
http://www.safariland.com/products/...ver/speedloader---comp-iii-11232.html#start=1
Another thing to remember is if you send you mooncipped revoler back to Ruger for repairs, all "non-standard" parts like your cylinder cut for moonclips will be thrown away and replaced with factory parts. It happened to me. UGH.
By the way, what is the guy in the video lugging around on his back?
If you reload or have enough $ to buy 357 magnum rounds, I suggest that you shoot that loudest and flashiest 357 magnum ammo possible at those darn Zombies. It makes for a great show and the wussified 9mm shooters will either cringe in fear or admire you as the second coming of Thor! Remington UMC 125 gr Jacketed Soft Point ammo is my personal choice to acheive this goal in remarkable fashion. Otherwise, handloads with Power Pistol, Longshot, or Winchester 296 / Hodgdon H-110 will put on a good show of sight and sound and will scare those Zombies away.
Enjoy your GP-100!
Chris
Chris