I set up my Remington 1100 in 12 gauge for hunting at Fort Knox several years ago...(Fort Knox does not allow you to have a "spare" gun in the truck...actually you are only allowed to have 10 shells with you)...

1. Remington fully rifled barrel with "open" rifle sights.
2. Drilled and tapped the receiver for a full length Weaver base.
3. Mounted a 3-9X40 scope in a QR Quad-lok ring

This gives me a scope for shooting out to 150 yards or so, but also open sights in case the scope fails, the weather freezes the scope over, etc.