C farmer i don't shoot with a duel injector but i have a set of the same clamps and i have had more blow outs more than good shot. So i bought the larger clamps and they blow out too. I can put my screws in and never have had a problem. I am thinking that the outside is not flat maybe where the screws have been installed. My thinking is maybe block the outside with some 180 sandpaper you should be able to see if you have any high places that are not letting the clamps hold even. I have seen these same clamps used with no problems so there has to be a problem somewhere.Cub48