The Mossberg 500 (M500) is a series of pump action shotguns manufactured by O.F. Mossberg & Sons. The 500 series comprises widely varying models of hammerless repeaters, all of which share the same basic receiver and action, but differ in bore size, barrel length, choke options, magazine capacity, stock and forearm materials. Model numbers included in the 500 series are the 500, 505, 510, 535, and 590. The Revelation 310 and the New Haven 600 were also variations of the 500 series produced by Mossberg under different names. By 2021, 11,000,000 M500s had been produced, making it the most-produced shotgun of all time.