[quote=PlantEater]
How exactly do Steam cartridges work in weapons? Are they pre-filled with steam, or does the steam only become created when the user fires the weapon? Also is there gunpowder, or are the weapons powered purely by magic steam? I'm asking because I'm trying to come up with a few pieces of weaponry for my character that are variants of the normal types, and what to make sure they fit in with what has already been established.
[/quote]

Steam Cartridges are essentially extremely powerful canisters of compressed air.The tech used to make them makes them more powerful than gunpowder, which is typically used by smaller weapons like revolvers. Revolvers and select rifles use more conventional bullets, cartridges with gunpowder charges in them, but for the most part Steam is king of firearms.