The Lee Conical .450 works in the Remington. Lee Conical .456 is made for the ROA and the Rogers & Spencer. The Lee .456 conical is too large for the Remington and Colts.
The Lee conicals have small tapered bases to allow them to fit the chamber mouth. They should only be cast from pure lead. The spru cutter will damage the base if the bullet is too hot when cut. The base will not fit the chamber if smeared by the spru cutter.