In my recent (H/H) Ottoman invasion of the Cherokee lands (now that's a re-write of history!), I came accross a similar situation at the hands of the notoriously elite native artillery.

Basicaly, they completely out ranged me -even though I had Ottoman 24lb'er foot artillery with a couple of chevrons. I know there are many threads complaining about the North american Indian forces complete inconsistency with history, so i shan't dwell on that particular issue. I guess it's just another case of one rule for the AI, another for the player.