I bought a ruger 10/22 with the collapsable stock for my wife. It came with a straight piece for the butt to slide on but also came with an angled piece you can change out for the butt to slide on to lower it down on your shoulder and see the sights better. Here is my question, how do you change them out? I took the two screws out but I am having hell getting it out. Any help would be appreciated.