I have the older non fluted Katadin barrel. I use the 12ga. shotgun forend on mine. You have to change screws because the shotgun forends use a dovetailed boss, ala Contender barrel, with larger screws. The shotgun barrel is slightly larger but I like to put a spacer around the screws on my rifle barrels to float the forend anyway, and this works out great. GOOD SHOOTIN', Walt