You can rapid fire a single action revolver by holding the trigger and “fanning” the hammer.
Is that a machine gun?
https://www.youtube.com/watch?v=b_7XR1L7NPI
Video short of Tuco The Ratt shooting a triple shot with a single action colt revolver:
https://www.youtube.com/shorts/Cm3Hi4rw-rk
Video short of Tuco The Ratt shooting a quadruple shot with a single action colt revolver:
https://www.youtube.com/shorts/2FpS2NGyNDw