Shop › FN BBL M16 BB 20" RIFLE LENGTH 556 FN BBL M16 BB 20" RIFLE LENGTH 556 $279.00 FN America Barrel, 20", 556NATO, 1:7 Twist, Button Broached, Rifle Length Gas System, M16 Contour, Fits AR-15, Matte Finish, Black 20-100043 Quantity: Add To Cart Added! FN America Barrel, 20", 556NATO, 1:7 Twist, Button Broached, Rifle Length Gas System, M16 Contour, Fits AR-15, Matte Finish, Black 20-100043