I know of no source for RIC ammo.
If he attempts to roll his own, BLACK POWDER ONLY!
I can't stress that enough, the RIC revolvers, and the earlier Webley .455 military revolvers simply CANNOT tolerate even miniscule loads of smokeless powder.
"The gift which I am sending you is called a dog, and is in fact the most precious and valuable possession of mankind" -Theodorus Gaza
Baby Jesus cries when the fat redneck doesn't have military-grade firepower.