How can I crown a Witch that is standing and wandering around?

I started playing Left 4 Dead 2 a while ago, and just noticed that on some levels the witches stand and walk around. While playing, I heard a person crown a witch while she was standing,

How is this done?

Commonly everyone started to shoot at the witch when she's on the ground. and It's OK, because she's a dangerous foe. That's the normal playing.

But for extreme players crowning a witch is to run towards her, alone, wait till she stands up, put a shotgun in her head, and kill her with 1 shoot.

Be careful not every single weapon will work, use a combat shotgun. You will learn better here

Wandering Witches appear in campaigns that are set during daytime hours, such as Dead Center or Hard Rain.

Crowing a witch (killing it in one shot) can still be done on wandering witches, but is much more difficult than their stationary counterparts. To crown a witch you must deal 1000 points of damage to her, which can only be achieved by using shotguns.

Contrary to popular belief, this does not mean a headshot is necessary. If you can get close enough to a witch that every buckshot pellet hits her torso you’ll deal the requisite damage. Headshots likely do more damage, but a small moving target like that is more trouble than it’s worth.

No matter what you’re aiming for, you must make sure to crown a witch in one swift movement. Taking too long to line up a shot is dangerous as she’ll move when going from calm to aggravated. In practice, the best way to crown a witch is to approach from behind so torso is the most exposed and fire before she has time to respond.

This can be achieved with the Tier 1 pump shotguns, but is much safer with a Tier 2 semiautomatic shotgun as it is easier to perform follow up shots if the first one doesn’t kill her.