3-pounder gun, 3-pounder, 3-pdr or QF 3-pdr is an abbreviation typically referring to a gun which fired a projectile weighing approximately 3 pounds. It may refer to : * The Grasshopper cannon : of the 18th century * QF 3-pounder Hotchkiss : Hotchkiss 47mm naval gun used by many countries from 1885 * QF 3 pounder Nordenfelt : Nordenfelt 47mm naval gun used by many countries from 1885 * Ordnance QF 3-pounder Vickers : British Vickers 47mm naval gun of World War I and World War II * OQF 3-pounder gun : used to arm interwar Vickers Medium Tanks