A gun is a gun. It is designed to shoot things.
A gun is not an all purpose tool. A gun is not a club. A gun is not a prybar. A gun is not a bottle opener (the Galil aside). A gun is not a tool for breaking out windows.
Bad things can happen when you use your gun for things other than shooting. For example, if you use your gun to club someone (no matter how deserving) you may mar the finish. Blood does awful things to a gun’s finish, especially the beautiful bluing on older Smith and Wesson revolvers.
Hitting things with your gun can also bend parts. Then your gun won’t go off when you need for it to go off. As the great Peter Hathaway Capstick once said, “The most terrifying sound in nature is not the roar of a charging lion, nor the whistle of a descending bomb; rather it is a click when you expect a bang.”
But the worst thing that can happen is that your gun might go off when you don’t want to go off. (I’d almost be willing to argue with Capstick that the sound of a “bang” when you expect a “click” is even more terrifying. However, I haven’t spent much of my life hunting lion and elephant in Africa, more’s the pity.) For example, when you’re breaking out a car window.
Bad move, space cadet. (Edited to add: Just to make it clear for my readers outside Texas, “Humble” in this case is a city near-ish to Houston, not a description of the police officer.)