Somewhere I have seen a full musket with a trigger guard like that. Since I am just across from Canyon, and we are just a short hike up from Mexico, you see all sorts of begged, borrowed, and stolen items which were smuggled across the border over the years. In its several fracas' over the years, Mexico took surplus weapons from anyone that would give them away since they never developed any industry of their own. If you all recall, I posted that short Prussian Calvary Carbine some time ago that is in the local Museum.
I just got tickled when I thought about a canoe gun down here in the desert.