Modern guns are safe to carry with a round in the chamber. This nonsense comes from old guns without safeties and breakable half-cock positions that will go off if the gun is dropped and hit on the hammer.
If you don't have a round in the chamber and you are attacked, you not only have to pull your weapon, you will have to rack the slide to chamber a round.
"Pardon me, Mr. Attacker, it will take me a few moments for me to be ready for you. Would you mind waiting?"
I prefer not waiting. . . or asking.
Same thing applies to the pump shotgun foolishness. Rack the slide so as to notify Mr. Attacker where to shoot.