My strat if you can't hit it 'cause your aim is as bad as mine: first normalerweise shoot them with a good ol' longneck rifle unter the argi flees; when it starts to flee, immediately switch to a loaded crossbow (laden with tranq arrows, of course) and shoot the argi with the Crossover, so you won't waste time with reloading your other weapon, like the rifle, because then the argi would have time to flee, and you don't want that. (Works only with max. Lvl 6 argis, sorry)