i am entertained by the shortsightedness of those in this thread it has to do with chemistry and physics, also several posters on this thread have not even read the replies before them so they view as rambling clones. guns can fire due to the fact there is a chemical mixed with the oxygen and sulfur which contains oxygen and when the hammer strikes the primer it causes the compounds to mix and give the force necessary for the slug to travel out of the chamber at high speeds. if you want a argument of halo defying laws of reality research before you open your mouth.