Chick here is a picture of a roller release and the lug (loop) that had to be filed to make it work. This is a beavertail for-end put on a hammer gun, and the reason for the release it two fold, one, the beavertail had the banjo cutout already and two, just relying on the "J" spring to hold it on usually does not work. By the way this hammer gun along with it's original barrel has now 4 other barrels for it, the latest being a 32" Specialty Grade with a ventilated rib and screw in chokes. The other barrels snapped right on, the only barrel that needed fit was a 32" Field Grade.