40 yards is a long ways in actual hunting conditions. 30 yards your set-upis fine. But 40...unless your a fanatical great shot......the deer is broadside......looking away.....standing still......with no wind......and you got your range finder on it....pass. There's way to opportunities inside 25 that are almost automatic. You can practice 3D all day at 40..50 and 60 and pipe the kill zone....but on a live deer at 40 its another story.

Good Luck!