In my experience,plastic wads do act as a shot concentrator;such that even in a cylinder bored gun resultant patterns approach that expected from a barrel with .015-.020 inches of choke when using cartridges with fibre wads.Is anyone else of the the same opinion?
Yes...I've experimented with paper shot cups in a cylinder bore to get a better pattern at longer distances and they do add a few more yards...my trouble was that try as I might, every now and then I'd get one that didn't open and it would sail through the target like a 'slug'.
As difficult as it is to get a turkey in range, I decided it wasn't worth the risk and had a barrel Jug Choked 'Full' instead.....now its just powder/wad/shot/card.....and enjoy.
Plus...with the cost of all the gas for range trips, and powder/wads/shot used for pattern testing, I could have had 4-5 barrels Jug Choked...