They probably mean an old revolver such as the 1851 Navy revolver. See the loading video here https://civilwarhorror.blogspot.com/2011/12/how-to-load-and-...

The barrel of the revolver is effectively 6 terribly short smooth bore muskets. Be sure to load them before the shooting starts. Then you can fire six shots in rapid succession, before changing to your other revolver. You did remember to buy two?

You load all six chambers, or five if it’s an antique without a firing pin safety. Typically this is accomplished by pouring the powder charge into the front of the cylinder and then placing a lead ball on top of it and ramming it into place, although one can also remove the cylinder altogether with some models and load it externally.

The end result is you can get 5-6 shots off quickly, but reloading will take rather a lot longer than with a cartridge firearm. This is one reason people carried two revolvers in the old West. Needless to say they’re of little interest to criminals, but fairly popular amongst sportsmen and re-enactors and such.

Not always. One of the biggest advantages of a revolver is that if you have a misfire you still have your next chamber waiting for you. That doesn't go away.