Lee Enfields?
Still too much firepower IMO.
I propose issuing them Brown Bess’ or some other single shot muzzle loader.
You are both far too charitable.
I’d practice non-interference: Whatever they have as a weapons system that they themselves have developed, let ‘em keep right on using it. (Plus, of course, insuring that all around you follow the very same rule(s).)
The natives may very well be throwing stones and poking one another with sharp pointed sticks today; If natural selection can still be assumed to work, it shouldn’t take many generations before they’re making their very own Brown Bess’s...or F-22’s...or Tzar Bombe’s and still be “that many generations” behind whatever we’re using.
I’ve just got this thing about keeping an edge on any potential adversary. Or friend, for that matter.