Uncle Matt,

On a few of the shotgun models like Leupold there is no mention that the scope has been designed to handle more shock.

Just from what my shoulder tells me, I think a 300 WSM, 300 Weatherby, or even 7mm mag kick as much or more
than most 12 guage shotguns or muzzleloaders (I only shoot 100 grains though).

I believe that a quality scope can withstand the abuse of large magnum calibers, ML or shotgun without being specifically designed for ML of shotgun. The Nikon Pro-Staff is half the price of their "muzzleloader" scope and for me it was not worth the extra money for the muzzleloader.