A deer can probably drop it's body weight faster than 1/5 of a second (0.2 seconds) because of the natural pull of gravity. I believe the natural pull of gravity is around 32 feet per second, so a deer could drop 16 inches in .04 seconds.

By the way 1/5 of a second is about how long it would take a 300 fps arrow to travel 20 yards.

The question is reaction time. The deer has to hear the sound, process it and THEN react to it. Whether a deer could do that in 1/5 second I don't know. My experience has been that deer usually freeze when they hear a sound, not drop and bolt.

I have seen video where it looked as if deer were ducking the shot from a muzzle loader and rifles. I highly doubt they can react that fast, but the video sure made it seem that way. That would mean they were ducking bullets before they could actually hear them, which would mean they could sense what was happening before it actually happened.

Pretty scary huh.

Paul