I don't think you would have time to know or feel anything after being shot. If this is a joke, it seems in bad taste to me. Nonetheless what a terrible waste of human life.
You will be very lucky if a bullet hits something to make your blood pressure drop too fast. Its not the most common way bullet injury plays out.
And most deaths are rarely instantaneous, in fact I feel even getting shot in the brain isn’t instant but rather leaves you alive and bewildered for a few seconds until you die.