I don't know they seemed to make a "Whooossshhhh" sound when I hit the release, espically in the woods where it was calm, I doubt the deer even if it could hear it, would be able to "duck" before it was already through at closer ranges, but what about the 35-45 yard shot? Maybe I should just try them in hunting situations, my brother in N.M uses them while Elk and mule deer hunting, who knows....