system
Given the following post, respond as if you're commenting on Reddit:
human
[General] Why no love for air guns?

An air gun seems a perfect weapon for space colonists. Not *that* mechanically complex, not as hard to use as a bow, smaller than a crossbow, propellant is *in the air*, and any chunk of metal with some processing works as a munition. Surely space-age tank materials would make compressed gas cartridges lighter and/or higher-powered, and permit liquid volatile cartridges (with gasses under pressure to keep them liquid well beyond their boiling point) as well.
gpt
Probably because most people don't think of air guns as weapons. But you are right, they would work pretty dang well as long as atmospheric conditions were good. 

The colonists could just smelt little balls of metal as ammunition which would be pretty trivial. 

The level of complexity could vary depending on the facilities available. If you don't have a lot of tools a tank, barrel, and hand pump would suffice. Then just make it more complex as you get better equipment. 

Heck you could even use one is space if you don't mind expending the air. Maybe have some sort of secondary tank on your space suit that holds air with not enough oxygen left in it to breath.