Thought I missed

This one was directly facing me, sitting up chewing away on something. Took the shot from 21 yards, Diana 34 .22 JSB 15.89gr dome. Did not hear the customary sound of pellet hitting squirrel. In fact, I heard nothing. Squirrel ran to the nearest tree, ran up about 20 feet, turned around and stopped for a couple seconds facing down, then started down the tree and suddenly leaped away from the tree hitting the ground DOA. What the heck? Thought I missed not hearing that sound but didn't hear or see the pellet hit the ground either. Turns out I hit the squirrel square in the middle of it's chest which is exactly where I was aiming, but no sound?. That's a new experience for me.

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