Autocockers are FAAAAAAAAAAST, the problem is the feeding. An autococker is friggen fast, faster than anyone will ever be able to pull the trigger, but over 13 the closed bolt style doesnt feed correctly its limit is about 13, with some TOTALLY tweaked things you can get 14. The less weight u have to move the faster it can open leaving it more time for feeding. Force feeding it a bit faster, but is hard on the balls. With a cocker they are a nice stable gun to shoot so they are easy to hit ball right after the last ball. So i say that you dont need over 13.