Doug K,
1"x14 RCBS dies are in Group X - pricey and you'll need a press
that accepts 1" dies.
Keep in mind that there are different 500/450s. That's why a chamber cast is a good idea. Were it me, once I had the cast, I'd send it to Superior to match it up with their ammo. Keep in mind that when your rifle was made, cartridge and chamber dimensions hadn't been standardized. Superior sells cartridges in 10-round lots. Buy ten and shoot them. Send sample cases to RCBS to see how they match up with their dies. If you're not using 'basic' brass, 7/8"x14 dies should work fine. Given how much you'll shoot it - you might decide to just buy loaded ammo from Superior. A proper reloading set-up (press, dies, scale, powder dispenser, trimmer, etc) will cost about $750 to 1K.If you're not an experienced reloader, this is a difficult place to start.
http://www.superiorammo.com/customammunition.html
