With the anti-terrorist programs in full swing the .460 would not have the .50 caliber problems to deal with. You can always load a .460 (or have it loaded) down to 2400 fps. .45 bullets are common and so is .460 brass.

.50 calibers can have feeding problems. They are so long and fat that binding is a real issue. Even expensive, brand name customs are known to have this problem.

If I were going .50, it would be in .500 Nitro Express in a double. In a bolt I would not trouble myself with anything bigger than a .45 of some sort.