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When the trigger is pulled, the bolt is no longer restrained and it travels forwards as a result of the compressive force stored in the spring. The movement of the bolt unblocks a valve, through which runs compressed air stored in a tank.  The rush of air drives a paintball out of the barrel, and the 'blowback' air pressure resets the bolt back into its starting position. position \cite{BlastzonePaintball:2012}.  Paintball is a very popular recreational sport played indoors and outdoors, in various senarios, and on different fields. The maximum muzzle velocity of most paintballs is 90 m/s, at which point paintballs begin to shatter in the barrel from the explosive force of the air, and also higher muzzle velocity becomes a safety concern.