The Gatling Gun was classified as a "manually operated, repeating firearm" as I recall. It never was a machine gun.
BTW, interested parties might take a look at Major, later Colonel George Chinn's book, actually books on automatic weapons. According to the text, the Gatling Gun was a TOE weapon of the U.S. Army as late as 1911, which kind of surprised me.
Also, some years back in Gun Week, I came upon an ad for an estate sale, containing a large number of guns. Included therein were, as I recall, several Gatling Guns, at least one in 30-06. That too surprised me.