According to Holmes, Colonel Moran is "the second most dangerous man in London."

Moran, Moriarty's second-hand man and top assassin, was only in one story "The Empty House" However, he is mention that he was with Moriarty in "The Final Problem" and try to take out Holmes when he saw his boss fall down the falls in Sweden.

Anywho, that gun he carries his speacial custom-made air gun, able to shoot at least ten feet far...or so....I think. Anyrate, I remember it's an air gun. He's very skilled with it, for he shot it straight in the forehead of a wax dummy of Holmes, from across the street, in an empty house room window.

So...yeah, that's it for now.....

Colonel Sebastian Moran (c) Sir Arthur Conan Doyle