Jamie is not genre-savvy. He does not know that he is in a comic strip, he does not know that he is a main character, and he does not know that being held up multiple times with the same gun is his creator's idea of a running gag. It is an entirely illogical, irrational assumption that this would be the same gun. Glock nines are common.
By the way - and I can't believe I'm typing this - DO NOT DO THIS.
I don't care what nifty trick you saw in an action movie. I don't care what the self defense video on Youtube claims you can do. I don't care how fast you think you are.
Always assume a gun is functional. Always assume a gun is loaded. Always assume a gun has a round in the chamber. Always assume a gun can go off at any time, for any reason. Always assume that if a gun goes off in your vicinity, especially if it's not being held normally, especially in a confined space, that it will hit you and it will kill you. That is gun safety 101.
By the same token, always assume that someone carrying a gun is going to shoot you. Maybe they think you murdered their son. Maybe they think you're a crazy racist serial killer. Maybe they believe you're a space alien or a demon in human form. It doesn't matter. If someone you don't know has a gun, assume that they can and will shoot you with it for any or no reason.
This is a particularly practical assumption to make if that person is pointing the gun directly at your torso.