you need to balance your hpr and lpr take your lpr out all the way and screw it in until it barely cycles and screw it in another 1.5-2 turns in should chrono to roughly to 280 if your hpr is set at 300 you must balance them accordingly but if your marker wont chrono at 280 with the hpr at 300 and the lpr set correctly turn them in equal amounts to get the desired velocity