Collet #4 for Original Case Trimmer and Power Trimmers. #4 Collets manufactured after January 1, 2010, have 2 steps.
Step dimensions = .310" & .605".
Fits:
33 Winchester, 348 Winchester, 38-50, 416 Weatherby Magnum, 416 Rigby, 416 Remington Magnum, 45-90 WCF, 45-70 Government.
For unlisted calibers use the cartridge head diameter to select the appropriate collet.