Corbin,
Just wondering - do you think if the action is properly bedded, there is really that much risk?
Don't you think the existing recoil lug as well as the barrel band sling swivel add some measure of resistance to recoil damage?
Also, does a .505 really have that much more recoil than the .416? Having never owned or shot a .505, I wouldn't know. My .416 has a recoil lug but the swivel ahead of the forend. My .500 has no recoil lug and no swivel through the stock either.