I agree with you. I think it's more likely they would have just used fire iron/hot poker to ignite a primed gun, and if it shot an "arrow," it would likely have been more of a bolt, and would have probably fit the bore a bit better. Hard to say for sure without an account from that culture or any more artifacts. Still, I have seen the serpentine style ignition system on handgonne, though usually on later ones, and I do know that around that time, there were incendiary arrows shot out of guns.