Two things, if you gun has RemChokes, put the Improved in...If it has a vent rib, put sights on it...Williams use to make sights that attach to a vent rib...
I shoot Remington Sluggers out of a '75 vintage 1100...It has a 21 inch, improved barrel with open sights...At 75 yards it will put them in a 2 inch group...
This is your cheapest option, rifled slugs can be pretty accurate if you find what your gun likes...You could also buy a slug barrel for that gun but it's gonna cost you...