Yes,
Both cartridges were invented in the early 1990s. The 550 Express, invented by Neal Shirley, is a shorter version of the 550 Magnum so that it will fit / function in a standard length action. This 550 Express was advertised as having a Pac-nor barrel. I spoke with Neal and he indicted barrels were available from Cutrifle Barrels in Prescott, Arizona, Bausksa Barrels, Pac-nor, and Badger barrels. None of these barrel manufacturers have been of any help in determining the maker of the 470 Capstick, or the 550 Express rifle.
