Ive seen many of shooters have this on the end of the barrel. Its either to the left of the right of the sights about 3 in long give or take and comes up about 1/4 in or so. It hard to describe but it looks like its used to make sure you dont look to far infront of the bird. I dont know if im right. If anone knows what im talking about can you tell me what it is and what it is used for?