I like how pistols make a cocking sound when pulled from their holsters...
Or the sequence of clicking sounds as every safety is taken off. The situation isn't serious until you hear those sounds.
This replaces the mandatory manual cocking of a double-action revolver from the early days, when only DA revolvers were used. You could have the muzzle stuck in your ear, but only when you saw and heard it being cocked did you have to start worrying.
And nobody replicates the loud, distinctive sound the of "AK clack", the sound of an AK47 safety being deactivated. Assuming the shooter realizes in the first place that an AK47 even has a safety.
I want one of those pump double barrel shotguns like
Moe on the Simpsons has!