It's called "string jump", but it's the ducking down they do prior to the actual jump that causes us to miss completely [best case scenario] or hit higher than we were aiming at on the animal. You cannot get an xbow quiet enough to change this, don't waste $ trying. Keep your shots to 20 yds or less starting out and aim for the heart, if they duck you still get the lungs. You might be able to find videos on youtube if you look hard enough. Amazing animals!