A deer's front shoulder covers about 1/2 of the heart and when selecting where to shoot, I aim for the 2:00 position of the front leg - placing the crosshairs straight up the rear portion of the front leg and squeezing the trigger when they are about 1" below the top of the shoulder.
Aim for the heart. If you're a little off, you still hit the lungs, anyway. Also, if the deer jumps the string, better chance of a hit if you aim for the heart. (imo)
Dave has a excellent point, however, I always aim for lungs but aim low in case the deer ducks at the release, actually they jump but they will be crouching when the arrow arrives unless its a long shot or they catch movement of your draw.
Here is the scenario... you sit in your 2 piece climbing stand and your foot inadvertently bumps the lower section while there is no weight on it - and it slides down the tree, out of reach!
OK, you are safe - you have a string tied from the upper section that you are sitting on and the foot portion that slid 4-5 feet down the tree. All you have to do it pull the other section up, reposition it and you are back in business, correct?
Have you ever tested this theory?
I have -...