Assuming you use pure lead you might can use .459's as is. May be a little tighter to load. If they're too tight you can get a sizing die and resize them to .458. Assuming you have a reloading press. If not you can pick up a cheap one on ebay. Somebody used to sell sizing punches you just put over the bullet and drive it down with a rawhide hammer but I haven't seen one in a long time, don't know if they still make them or not.