The few that I've taken out have been stamped with the specific cartridge. I have a 30-30 with a .303 stamped rotor, don't know why. It's a 1923 featherweight takedown. When loaded the cartridge counter numbers don't line up properly with the receiver window - the 303 has a fatter case than the 30-30. The other 30-30s I've seen line up Ok. Leads me to believe the 303 and 30-30 rotors are different, but with some amount of interchangeability.
