i never used an automotive red primer on these tanks i have just the one and painted another for someone else i just when directly on the plastic with acrylics
but Krylon is a paint for plastic it is advertise as that so maybe thats why some have used it i don't see a problem using an automotive red primer on it if used through an airbrush i think with using a spray can you put on too much paint and where you have a small detail on your tank painting it with a spray can you would lose that detail from the paint build up the airbrush puts a nicer finish on not too much paint so that you can keep these small details i just spray my paint from the spray can into the airbrush jay i get it on my hands but i'm use to it you do get overspray flying around doing this so make sure it's not around anything you don't want paint on and wear a mask while painting even just a dust mask for the vapors as far as the history of the use of the red primer i have no idea someone else may have to answer that one...lol

Greg