A dramatic scene early on in my madness for all things Fehnnik. Since I have the whole of the history of the planet to play with, I can go from nomadic paleolithic hunter-gartherers to bronze age pre-imperial to classic First Empire to pre-technic to star-faring.
The gun is a muzzle-loading rifled musket with percussion ignition, which would be eventually up-graded to piezo-electric ignition. Breech-loading and metallic cartridges would be slow in coming, not until the Neo-Imperial Wars some centuries later.