Safe and empty weapon, pull back the slide and lock it, drop one (1) primed case into the chamber. With the barrel pointed in a safe direction, drop the slide
If you have a 1911, do not put a round in the chamber and drop the slide.
Actually, if you have any pistol you care about, don't put a round in the chamber. Certainly not twenty times,
Some may put up with it, some may not. It's not good for any of them.
The pistol is designed for the case rim to slide up under the extractor as the slide moves forward. The extractor is not designed to "snap" around a chambered round.