Atlaw +1, BUT, it could be the screw is too long and entering the receiver ring and binding it up. That happened to me before as well. Take some lipstick or something and coat the bottom of the action around the screw hole and tighten it gradually until the bolt won't function. As soon as the bolt won't move, stop. If the action is bottoming out, you'll the lipstick on the stock. If it's not, you'll know that the action is bending.