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Experience is achieved when the activity becomes muscle memory. It is hoped that soldiers who need to return fire do so instinctively, in response to the external world, in a way no different than expecting an oncoming car's behavior in an intersection.   \subsection*{Paintball \subsection{Paintball  Markers} FOR SAM TO FILL IN WITH WORDS AND THINGS A paintball marker derives its name from its original use by forestry departments and cattle ranchers to respectively mark trees and cattle with paint from a range.   The operation of a semi-automatic blowback marker like the one used in this experiment involves a metal bolt on a strong spring, cocked in a back position and held in place by a spring-loaded trigger mechanism.   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.  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.  In any case, proper protective clothing must be worn, including a face mask that protects the head and throat.   Paintball barrels lack rifling, and as a result markers are generally imprecise. Maximum effective distance is approximately 30 m.