Some years ago I was using large buttons with the screws that came with them with no issues on my own personal launch rail and when I tried to use a club launch rail the screw head would not allow me to load the rocket. There seemed to be some differences in the rails as far as depth was concerned. I never did figure out the difference. Some said one rail was metric and the other standard American but not sure that was it. I thought maybe the club rail, the one that didn't fit was just loaded up with stuff from many launches. anyway my remedy was just to grind down the top of the screw. Then it worked on both. Since then I have just been using lower profile screw heads. I'll be interested in seeing others' answers.