It sounds like your gun is new enough.
I was always told slugs could be shot in a gun in good condition as long as it was NOT FULL CHOKE or smaller.
They will impact differantly depending on distance because SxS are regulated to shoot at a certain distance. Also the bead sight is not really made for aiming like you do a rifle. But obviously people have shot a lot of critters with a bead sight. Soif you do dicide to use this shotgun for slugs just see how it shoots before going hunting. (I know that is stating the obvious)
Good luck