I had an 11-87, mine didn't cycle well with lower end field loads and never had much accuracy with the rifled slug barrel and cantilevered scope mount. Good luck in your quest.... I switched to the Ithaca deer slayer using 3" brenneke golden slugs, kicks like a mule but accurate, grapefruit diameter including fliers, at 100 yards.

Next change was the encore rifle system, I now have a half dozen barrels including the 20GA rifled slug barrel. Using remington copper solids, 2 3/4" it delivers the grapefruit group at 150 yards. I would not hesitate to shoot this combination at 175 yards.

There are many accurate combinations out there though the same model gun and barrel may give different results. Best bet is to work on the issue prior to the season starting (as previously stated.) Good luck with next year's accuracy....