Is death instant from a gunshot to the pulmonary artery?

Unconsciousness should occur pretty quickly with a GSW to the pulmonary artery, but death certainly wouldn't be instantaneous.

Despite what you see in movies, on TV and in Video Games, even a GSW to the noggin (head) doesn't cause instant death. The person may drop and never make a purposeful movement again, but the dying process isn't like flipping a light switch. Its more like flipping 40-50 light switches over a few minutes.