First Strike Rounds 100 Count .50 Caliber Clear Green Shell Green Fill. 50 caliber First Strike Round Green Clear Shell Green Fill in 100 count are great for those . 50 cal paintball markers. First Strike round or FSR as some say, make the perfect projectile for those extra difficult shots. First Strike Rounds have set the bar for consistent and accuracy in paintball. Utilizing both aerodynamic design and fin stabilization technology, First Strike Rounds maintain their velocity longer than a regular paintball. The