6s pattern better because obviously theres more pellets in the shell. but, while you may get more hits with them, they don't pack the same punch as larger sizes. its like the difference in getting hit in the face with four golf balls or two baseballs. which one does more damage? personally, i prefer 5s for the added power, but its up to you. you have to decide whether you want more penetration power with less shot or less penetration with more shot. as for killing a turkey at 40 yards with 6s, as long as you have a decent pattern at that range, then yes it will kill him dead as a hammer.