340 oil pressure? Help

post 27 - plug is in. post 48 - plug was missing. more info please
I've seen a few engines where the galley plug was missing. ZERO to 2 PSI. That hole is a HUGE oil bypass when the plug is out. I cannot see any way in heck the engine had the oil pressure it did if the plug was left out.
Yeah I'm calling the shop today and letting them know about it. I tried two different mechanical gauges to make sure one wasn't bad. Really hoping it's not fucked up lol