BTW, if that gun you said has .455 throats, has a .454 groove barrel, you should get good accuracy with .454 or .455 bullets. However, IF the gun has a .451 groove barrel along with the .455 throats, which, being 30 years old, is highly unlikely, it might be best to run softer, rather than harder bullets, say BHN 12, thru it to guard against an over-pressure condition. jd45