Everybody loves guns! Well, by relatively new I meant 'last hundred years or so'; this isn't radically new technology and other similar stuff (for clearing rockslides and so on) probably existed before then. We're probably talking early flintlock level here. In the Upper Caverns, they're a status symbol, and are probably comparatively widely used in duels and so on - and there's the space for deploying musketry. Once you get further down, you usually want to avoid detection, and there's often not the space for muskets to be of use, so anyone wise prefers quieter weapons - small crossbows are probably the weapon of choice. Down here, pistols become a last-ditch weapon or more usually a prestige symbol.