Re: General firearms care question
What you may be thinking of is letting the bolt slam forward on a manually chambered round.
Especially on pistols, that's a poor idea and can damage the extractor, which is designed to have a cartridge slide up from the magazine underneath the extractor hook, rather than having to cam outwards over the rim of a cartridge dropped manually into the chamber.
If there is no round in the chamber, though, either on a rifle or a pistol, it does not hurt anything.