A fictional martial art developed for the 2002 film "Equilibrium" starring Christian Bale.
Supposedly developed by analysis of thousands of gunfights, which apparently developed into the idea that it is statistically possibile to determine where any individual is located and where all shots will be delivered from in any particular gunfight.
General practicioners of this martial art are "Grammaton Clerics" in the film "Equilibrium," who are drilled in the "katas" (routines practiced and memorized by rote) in order to use their firearms as an extension of the self.
While visually appealing, Gun Kata has very little real world application as it discounts enemies that attack from the prone position or from ranged attackers (such as snipers).
The Grammaton Cleric used his Gun Kata to weave his dance of death in the enclosed room. However, the sniper on the roof across the street made an excellent headshot when the Cleric decided to sillouhette himself in the light of the open door.