My son just purchased a Lyman .45 cal Plains Rifle in great condition from a gun show. Subsequently, we learned that the .45 cal rifle is no longer sold and was last produced in the 1970s. Concerned about spare parts, we inquired with Lyman Products and asked if parts (except for the barrel) from the presently made .50 cal Great Plains Rifle could be used for the .45 cal Plains Rifle. The answer we got back from Lyman was, "Don't know." Having said that, would anyone know if the parts between the .45 cal and .50 cal. are interchangeable and if not, who would be a source for parts on the .45 cal Lyman Plains Rifle? Thank you.