This is an expression related to the blueing of a gun - specifically a high-end shotgun. In the South especially, a finer shotgun would have a "blueing" or a "blue" of the steel that was accomplished by way of the quality of the steel and the effort of the person who owned the gun polishing it. "Shotgun shine" is a simplification/symbolism of this concept and a way of saying that a person has a killer instinct; however attractive they may be. It's not necessarily a positive expression, and surprising that in the nearly 25 years since Alabama 3 used it, and since the Sopranos used it in this manner exactly, that no one else has put it on Urban Dictionary.
It's a shame about little Johnny Sack - he's got such potential in real estate, but also that shotgunshine.
A term used in the southeastern part of the United States to describe the character of someone who’s very charming, definitely dangerous, and certainly insane. These three qualities together are what’s meant by “shotgunshine.”
Women were always crazy about my daddy because he had that shotgunshine. He had the good looks of a leading man, the manners of an aristocrat and the morals of a bank robber.
Nickname given to bales of marijuana thrown overboard or out of airplanes. Origin is reportedly from members of the US Coast Guard in the area of Southern Florida.
"Base we've got some square groupers floating outside of Miami harbor."