[nickynickell]

They were joking, and you're being needlessly hostile. Plus you're wrong on multiple counts. Most of the counter examples are historic, but still.

Yes, barrel is not a unit of rounds, but there are situations where it would be appropriate. Superimposed loading is where multiple rounds are loaded in the same barrel and are fired sequentially. This is a very old idea, but for a modern take on it look up (the now defunct) Metal Storm. Terrifying stuff.

There have been guns with many more barrels than 7 or 8. Volley guns have been made with anywhere from just a few to nearly a hundred barrels. They weren't always big platform mounted monstrosities either. A famous example would be the nock gun: a 7 barrel, shoulder-fired flintlock.