I was going to essentially say this same thing so I'll just add there was also the Chambers 'machine gun' a flintlock naval gun able of firing 224 shots @ ~120 rounds per minute.

The technology we associate with periods of time isn't reflective of the peak of technology but more often the median. In the last army rifle trials a company was trying to get a rifle with caseless ammunition in service. That technology has been around since the 1850s and still hasn't been adopted by anyone despite it's obvious advantages.