What is the value of a single shot 12 gauge Keystone Arms Co shotgun?

The value of a single shot 12 gauge Keystone Arms Co shotgun can vary significantly based on its condition, age, and market demand, typically ranging from $100 to $300. Collectible or rare models may fetch higher prices among enthusiasts. It's advisable to consult a firearms appraisal expert or check recent sales records for a more accurate estimate.