Board Thread:General Discussion/@comment-5565348-20131016002708/@comment-5052376-20131018232950

It onl works when OXYGEN is present, and there is not enough Oxygen in Space for you to fire a gun. Wikipedia on Fire:

"Fire, in combination with a sufficient quantity of an  oxidizer such as oxygen gas or another oxygen-rich compound is exposed to a source of heat or ambient temperature above the flash point for the fuel oxidizer mix, and is able to sustain a rate of rapid oxidation that produces a chain reaction."

And Space:

"It is not completely empty, but consists of a hard vacuum containing a low density of particles: predominantly a plasma of hydrogen and helium, as well as electromagnetic radiation, magnetic fields, and neutrinos."

The Oxygen required to cause a flame or spark is missing. Thus, a gun cannot fire in Space.