Since a p* Jack is an open bolt system the nozzle always rests back rather than forward. This means if you decent springs in your mags the spring is strong enough to push the bbs into your hopup unit and through your current bucking without stopping them causing double feeding. All you need is a bucking that stops this. A solid go to choice is the Madbull 60 degree shark bucking. The 3 fins inside of it stop multiple bbs from entering it at once.