Have to agree with 505ED, components for the 450 would be more readily available, just by a quick check on the net. I have only fired a big 50 on one range visit, pretty sure it was the Jeffery, beautiful rifle, but quite a handful. Shot most of the 458's and own a few, so I am bias toward them for no other reason components and loaded ammo are cheaper. Having a custom 458 WM being built, so I would lean more toward the 450. Besides Rigby's have a great reputation.