The Girandoni Air Rifle was an airgun designed by Tyrolian inventor Bartholomäus Girandoni circa 1779. It fired a .46 caliber ball at a velocity similar to that of a modern .45 ACP and it had a tubular, gravity-fed magazine with a capacity of 20 balls. With a full air reservoir, the Girandoni air rifle had the capacity to shoot 30 shots at useful pressure. These balls were effective to approximately 150 yards on a full load.
More information: https://en.wikipedia.org/wiki/Girandoni_Air_Rifle
Hat tip to Michael Z. Williamson, who so eloquently stated “30 shot repeater in 1779. Because the Founders could never have foreseen high capacity weapons.”