Oh hell yeah. Warfare in Africa does seem to have been an alarmingly haphazard affair, with people who just fancied a bit of action turning up and serving as scouts or whatever in irregular volunteer units and as such they would carry whatever was to hand (or just stick with their own guns if they preferred). I think it's fair to say their performance and reliability could be hit and miss!
But the British Army does appear to have learned the lessons of the Zulu War the hard way and made sure that their regular colonial soldiers were well equipped and led compared to the other European powers in Africa. I think I recall some of the Portuguese native troops being equipped with black powder weapons.