I have shot many flats of steel T and Steel 2 through my Briley extended chokes. I use nothing but I Mod. They were recommended by Briley for my 3.5 Citori. The choke (constriction) is outside the barrel. Kills snows at 80 yards with 3.5 T's. My normal consumption is a flat of shells a season. The choke tube and the barrel still look good

bill