BuddyBo,,,,,, I've only shot at two bucks with my crossbow in three years. The first was a clean miss because I did not pay attention as to where the limbs on my crossbow were. The second was a kill. In both cases, I saw the bolt burried into the ground well before the buck responded. The buck last year was hit and the bolt burried in the ground about the same time I heard the string stop.

Aluminum bolts out of my Barnett Quad 300, fly at 337.5 FPS through my chronograph. I know my carbon bolts fly faster, just haven't put them through my chronograph yet. That's over 100 yards per second for speed. Depending on the distance the deer is from you, it will take just a fraction of a second for your bolt to hit the deer.

Tree Climber made a good suggestion of practicing with broad heads. G5 makes a PRE-SEASON MONTEC for practice. I used them last fall for practice to know where things were hitting and it gave me good insight as to where me and my Quad 300 stood. The attached address will show you. My stand was 18 feet up and the decoy was 22 feet out from the base of the tree. This was an approximate 8 to 10 yard shot using carbon bolts with a 125 grain pre-season Montec out of a Barnett Quad 300.

http://users.rcn.com/moxie1884/PA020001.JPG