[knightsljx]

Spoiler:

the gun fight between Harima and Hanai is a reference to the movie, Equilibrium. The technique they use to avoid each other's shots is called Gun-Kata and the scene where they fight melee range is the last battle scene in the movie between the protagonist and antagonist.
Also, the way Harima reloads and draws his guns using the gimmick in his sleeve is also from the movie.