Colt is not auto. And yes, almost any gun spams. the "meta-game", if any, is practically about dodging bullets, hence "spamming". The hit-box is so large in this game compared to the environmental space in which you can shoot in, what you people call "spam" is by far the most effective way to kill your opponent. Some people do spam far more often then others, but the basic tactic is still spam. This game is supposed to be a twin-stick/duel-stick shooter, and most of these type of games feature spamming as a viable tactic. Also note that because you can only shoot North, South, East, and West, it makes it extremely hard to effectively "sharp-shoot"

On a side note, the origin of spam is Monty Python^^