The Mossberg Defender Model 500A was is my first and still only shotgun. I’ve mounted a scope, fiber optic and even a laser to it before returning to the fiber optic sight.
Shotguns are still permitted to have pistol grips and collapsible stocks where on rifles these same features are illegal - why?
I’ve since gone back the conventional style of shoulder stock as the pistol grip made working the slide release and safety difficult.
This florescent green front sight uses a fiber optic rod to gather the available light and focus it into a bright dot.