Before there were fancy electronics in our paintballs loaders, we used basic gravity feed loaders. These rely solely on gravity to get the paintballs into your paintball gun. If you use a paintball gun that has very little recoil, the paintballs can often jam and not feed into your paintball gun. Just give your paintball gun a shake and you are back in action. If this happenes often. then you should look into upgrading to an electronic loader.