Originally Posted by robman2629
I have a 20" barrel on there right now.
A cantilever shotgun barrel is a barrel with a one piece scope mount base attached to it, to make it possible to mount a scope on your shotgun without tapping threaded holes for a regular scope base.
cool, never seen a 3 1/2" chamber in a 20" barrel!
that rifle barrel posted above looks like what I'd go for if I were you unless you think you will need longer shots. They can be surprisingly accurate, just buy a box of as many different slugs as you can find and test them out. Likely you will find a handful that do much better than others.
never mounted optics to a shotgun so I'm pretty unhelpful there