Friends, I recently acquired what I think is a Sheridan Model A Supergrade. I'm asking you to verify mine is one from the pictures below. You can probably tell I'm not an expert. And frankly, I'm kind of confused. I see guns with important differences being called a "Supergrade," and I see a Model A and a Model B. Can you tell me the difference between the two models and tell me what mine is? Anyway, here are the pictures.... If you need additional information, please ask.