FWIW, I followed up with CCI regarding the use of 22 WRF ammo in 22 MRF firearms. I was told, in a circuitous manner, that as a good SAAMI member, they could not recommend using any cartridge in a firearm that it wasn't originally intended for. The guy I spoke to also said that the 22 WRF bullet has a slightly larger diameter than the 22 MRF bullet, so in a revolver it might be possible for the jacketed 22 WRF CCI bullet to lodge in the barrel and let the gas escape out the gap between the cylinder and the barrel, thereby creating a dangerous situation.
Jeff
