Either way I would call 911 immediately to let them know what happened - in case he decides to call with a made up version of events, but also because what this guy did was wrong and should be reported. I WOULD mention the gun if there is any possibility that he actually saw it or might even infer that you had a gun (again, covering yourself in case he makes the first 911 call to report "guy pulled a gun on me".
Rolling down your window in such a fast-moving event seems to be a common problem (I know someone personally who did this - didn't even realize she'd done it - and the guy actually grabbed her shirt and tried to pull her out of the car
![eek6 :eek6](./images/smilies/eek6.gif)
Anyway, glad you're OK. Glad you were able to avoid the situation withOUT resorting to use of deadly force. Thanks for posting. And welcome to the forum.
![tiphat :tiphat:](./images/smilies/tiphat.gif)