I recently learned of the Konyak Naga hill tribe of northern India and Mynamar (Burma). Apparently, guns are a big part of their culture and they make them themselves.
The Konyaks' guns seem all to be single or double-barreled muzzleloading shotguns with percussion locks. They make their own powder and caps.
There are a couple Youtube channels with information about the Konyak Naga gun culture that I've been watching lately.
This video has an overview of their gun culture:
Target shooting at a pig's skull suspended from a tall pole (apparently the object is to cut the string holding the skull):
And this one shows how they make percussion caps:
Finally, this video shows how they make gun powder:
I find this fascinating just because I am into black powder and muzzleloaders, but it also gives a glimpse of what's possible with primitive tools, a lot of skill, and patience.