Yes, the Vulcan cannon is just a tiny bit noisy.
“Live long and prosper” is not what they heard right afterward.
When at RAF Bentwaters back in the mind-80’s, a weapons troop was working on a gun jam (30 mm), using some sort of tool to pull back the firing pin when he lost his grip and the firing pin snapped forward and hit the shell casing dead center and - BLAM - the bullet fired and skipped off the ground about 76 feet in front of the jet and then hit the reinforced hinged part of the Security line shack door just as a Security troop was coming out the door. LOTS OF CONFUSION, lots of yelling about a sniper using a 30mm rifle (yeah, right). Eventually the base came off of the lockdown and the weapons troop was found to be using an unauthorized tool.
They need to go to Chicago gangland outfitters and get a silencer.....