Hi, I've built a coilgun using a solenoid, but my projectile stops at the half of the road, but this way i can't measure neither the acceleration nor the speed. what could be wrong ? how to push it further ? I also have a question about the efficient methods to measure the speed of the projectile. i've thought about the accoustic method, but it was not efficient since the room where i do the experiences is not isolated. btw i study in France so excuse me if i don't use a proper vocabulary.