I purchase the Accura back in December and had a little issue with this as well. The screws that came with the Dura sight mounts seem to be too big for the threads in the Barrel. After a call to CVA to verify the correct size screw which it was. I went back and tried with what I thought was nothing to lose because if it was the right screw and properly drilled and tapped from the factory it would not be my fault is threads got stripped . It ended up being it was just real tight to get started but once you got past the first few threads they went right in. So give that a try as long as you have confirmed the screws you have are proper size.