Used to describe the act of hitting someone with the handle of a handgun while holding the barrel.
The "classic" pistol whip
originated during the mid to late 1800's with revolvers like the Colt Peacemaker. Because of the long barrel of the gun a person could actually make it into a powerful club like weapon by grabbing the barrel and using the handle of the gun to "whip" someone.
It is still used with today's handguns even though most of them make for poor pistol whipping for a few key reasons:
1. Because of the short barrel length, and
overall compactness of the gun, you can't really swing it with the force of an old revolver.
2. It is extremely dangerous to do with a semi automatic because of the
possibility of the gun discharging, often towards the person holding it, because of the trigger inadvertently being pulled in the force of the whipping.
Old style revolvers couldn't be fired unless
the hammer was already cocked, so a person could whip away with no danger of firing the gun as long as
the hammer was down.
Since a semi automatic keeps a round chambered at all times it is possible to discharge it with the rough shaking a pistol and whip uses.