Winchester Double X 12 Gauge Ammo 3 1/2" 00 High Velocity Buckshot 15 Pellets ammo review offers the following information; Double x ammunition provides ultimate high-velocity, knock-down performance in the field.With copper plated hard buckshot for long-range performance, double x has been trusted by generations of hunters who demand quality and consistency.Buffered copper plated buckshot, provides unmatched long-range performance, tight patterns and maximum stopping power. Double X ammunition provides ultimate high - velocity, knock - down performance in the field. With copper plated hard buckshot for long range performance, Double X has been trusted by generations of hunters who demand quality and consistency.