Never barked a squirrel, but when we were younger I saw my brother kill several by aiming his Marlin 39A to barely crease the highest part of a squirrel's back. Cut a tiny slot, and the shock/damage to the critter's spinal cord killed it instantly, with zero meat damage. It wasn't a fluke--he aimed the shot.
The guy who did the balloon trick, a gunsmith and trick shot named Badlands Bill something-or-other, was one of the featured marksmen on a History Channel piece which I recall was called "Sharpshooters". He also did the ricochet shot off a steel plate, if I remember correctly--may have been one of the other featured shooters, but somebody did it.
"Don't let macho be your epitaph."