I have a Colt SAA revolver , third gen. I am about to start casting 250 grain slugs for it and am not sure what Boolit sizer die to use. From what I have been reading, older guns use .454 size to diameter , and newer ones use .452. I am not sure if my Colt would be considered an older model or a newer model. What size sizer die would be recommended for my gun ? Also what would you that are using this combination recommend as a good medium load for it ?