WBLDon, rifled chokes can still be had as I just last week bought a pair for my CZ 12ga hammer sxs. They are made by Carlsons at
www.chocktubes.com I do know that in the past they would do custom work...maybe even on a 10ga, but as CptCurl said the paradox barrels were quite a bit heavier than a shotgun. I owned a nice Hollis with the invisible rifling and it's barrels were somewhere near 0.95 to 0.125 as I remember....shot a Fosbery style slug of about 700 grains with 26grains of 4756 to point of aim each barrel at 75 yards
