Ken you made me smile!
I was not familiar with this reference to a "Squirrel Barker" as a "good shot". Having spent my early years in Mississippi I did a lot of squirrel hunting in the "wilds" near my home. We sometimes used a wooden caller, similar to a "duck call" called a "squirrel barker", which made (with practice) a high-pitch barking noise that tended to arouse any surrounding squirrel's curiousity.
I've also seen a reference to a small caliber rifle as a "squirrel barker". The origin of this term may be related to the "good shot" theory.
I wonder when "new" visitors visit this site and see in ALL CAPS the term "SQUIRREL BARKER" what they think? :-) Sounds like an Indian name, huh?
Jim