extreme'
a couple suggestions: always hold the rifle butt/recoil pad tightly to your shoulder to limit the movement of the rifle once the cartridge is fired. i'd expect to reduce recoil velocity and movement of the rifle bydoing that. it should also help to keep a scope alive if the velocity and movement under recoil is reduced.
i like the new bushnell banner with the 6" eye relief. i put one on my new .270 weatherby vanguard last year and got excellent results with it -- being able to call my shots repeatedly. i think that is a product of both the rifle and the scope setup. admittedly, however, i put that shotgun/levergun scope on a bolt-action. it could be that it's just the ticket for a .450 Marlin.
www.bushnell.com will allow you to see it. the part number is 71-3947.
for others who need a scope with a long-eye relief and a good mounting length (for long-action cartridges like the .270 or .30-06) this scope may hold an answer for you.
i hope this helps,
ss'