did not know how to describe it. so got it of these forums put a hopper through it sweet as a nut was working great at the walkon after about 1000 rounds started to hick up, fires 1 to 5 ok then the bolt moves back and fourth like on traing mode with air but does not shoot properly tried new battery and filled up air. battery indicator reads full. took the grip off cant see anything in the grip loose or paint looks clean. any help would be greatfull.