With todays crossbows you have more then enough power to kill deer out past 50 yards, but that is not the problem, the time it takes for the arrow to get there IS!!!!!! Heck ....... even my 24 year old, 150 lb crossbow has enough power to do that, but out past 35 - 40 yards, time will be against you. At the longer distances, deer will have time to react to sound and move enough for either a miss or a bad hit, which is worse then a miss. Even if the deer does not react to sounds, it could just move (natural, dailly movement) to have the same effect as above.

IF your talking about larger, slower animals like MOOSE, then you can lengthen your distances out to maybe 45-50 yards.

YOu can hit accuratly out past 65 yard easily, Heck ............ over in Europe, they have compitations that shoot 100 - 150 yards and get groups of less then 6 inches, but the time from arrow release, to point of impact is just too great on a moveable target like an animal.