I once shot a .505 Barnes Supreme-like wildcat back in the early 70's, built on a ZKK BRNO action, light custom stock. It uses necked and blown .460 WTBY brass. The owner said the load was 124gr. IMR 3031, with 600gr. Barnes at something like 2,800fps. Total weight of the rifle was a scant 9 pounds with 4X scope. It spun me around like a weathercock. Guess I should have held it harder, not like my pet offhand match rifle. I put that one above my recoil limit. 1 shot was enough. His velocity quote seems to be about 100fps high of maximum.