Large bear traps are the most under used thing in the game. Get like 7 or 8 of the large variety and when you see a carno put one down between you and it, agro it, shoot transfer and rinse and repeat till he's down.
You just need a couple trank arrows, at least about nine, maybe some hide armor, and then climb up onto a rock that he can’t get up onto, then shoot him or something to Agro him, and once he comes to the base of the rock and attempts to kill you, shoot him with the tranks. Then when he tries to run away, just jump down and chase him. But make sure he doesn’t get KOed in water.