I'd put a fixed-power scope on a shotgun. Part of that internal works that can be hosed-up is the zoom mechanism. Also, lower magnification is to be preferred due to the limited range of a slug. 4X used to be considered the field standard, with 6X being reserved for antelope rifles.
Just something to keep in mind. They DID kill game back then, you know....
Just something to keep in mind. They DID kill game back then, you know....