I have always been impressed by the gunsmiths and gunmakers of Khyber Pass. And much kudos to these guys in protecting their homes, their families, and their land from the constant political strife that is overwhelming that region.
That said, the basic technology behind firearms is not that difficult to comprehend at all once you have grasped onto the operating mechanism of the ignition source, the propellant, and the projectile. Of course, building a fully functional automatic or muzzleloading firearm is much more complicated than building a longbow or recurve bow from a piece of fiberglass or spring steel bar stock that is capable of taking big game from 50+ yards away, but those who can apply the knowledge of how a chemical-propellant solid missile projector works into a functional piece of machinery will not find it too obstructive in creating functional and useful examples of such.