I’ll go first. Mine is the instant knockout drug. Like Dexter’s intramuscular injection that causes someone to immediately lose consciousness. Or in the movie Split where there’s the aerosol spray in your face that makes you instantly unconscious. Or pretty much any time someone uses chloroform.
Guns in general are a lost cause at this point. Even shooting a 22 outside is doing hearing damage, but plots rely on people shooting 9s and 45s indoors and having normal conversations immediately afterwards.
A 22 can penetrate all the way through a car and still be dangerous
Anything but a direct hit on the head or heart is going to take at least a minute for someone to die. Conversely, the chance of dying from a non-lethal shot (or having lifelong complications), even to an appendage, is nonzero.
At the same time, getting hit by most calibers isn’t gonna knock someone down or blast them back like they got hit by a car. Human skin is soft, very little energy is transferred into the body’s mass as the bullet travels through.