Requires Earendel's AAI Vehicles: Ironclad as my mod does not contain any of the needed assets.
Adds a machine gun variant of Earendel's Ironclad as well as a land-turret of the Ironclad's mortar that acts as a mid-game artillery alternative. Also adds poison and fire variants of mortar ammunition.
Has a minor visual bug where the machine gun animation plays when you're moving rather than when you are shooting. I'm new to Factorio modding so I'm still working out how best to fix this.

Earendel if you see this, feel free to implement these ideas into your mod.