"Shooter" depicts a number of sniper tactics, thanks to the guidance of former US Marine scout sniper Patrick Garrity, who trained Mark Wahlberg for the film. Garrity taught Wahlberg to shoot both left- and right-handed (the actor is left-handed), as he had to switch shooting posture throughout the movie, due to Swagger's sustained injuries. He was also trained to adjust a weapon's scope, judge effects of wind on a shot, do rapid bolt manipulation, and develop special breathing skills. His training included extreme distance shooting (up to 1,100 yards/1,006 m), and the use of camouflage ghillie suits. Fuqua appointed Garrity as the film's military-technical advisor.