You seem to be saying that if the majority of "back the blue" folks are gun enthusiasts, that means the majority of gun enthusiasts are "back the blue" folks.

You seem to be saying that if the majority of "back the blue" folks are gun enthusiasts, that means the majority of gun enthusiasts are "back the blue" folks. I'm not sure if either is true, but if it were, you still couldn't infer one from the other.