Well, I checked some of the same model I found sitting on a shelf in home despot, and found one that would accept the stop. So I concluded mine had a manufacturing defect not allowing the jaws to open that little bit more. Some grinding and adjusting got it, but the swaged diameter looked like it could have been bigger or something. There was flash where the radii of the cavities met like in a molded part. To try to improve that I will round the corners a bit. I will try to post some pics later. Thanks again.