with the Mark 5 were: In American service, the Mark 5 remained afloat (albeit in dwindling numbers) until 1930, when the last guns were removed from the Floridas in compliance with the terms of the London Naval Treaty. Survivor A Mark 5 Mod 8 gun is displayed at Fort Hamilton in Brooklyn, New York, representative of the general type of coast artillery guns the fort had. Incident During the summer of 1916, blew out her left hand gun in turret No. 2 during target practice. After an investigation of s guns it was discovered that copper deposits from the driving bands on the projectiles had narrowed the bores of the barrel enough that it caused the projectiles to slow down. This problem, known as "copper choke", allowed the pressure in the barrel to increase to dangerous levels. Lapping heads, to remove these deposits, were issued for all guns 12-inch and larger throughout the fleet. The lapping heads were later replaced by wire and pisaba brushes. Coastal Artillery Following the signing of the Washington Naval Treaty in 1922, many of the Mark 5 guns in service were removed from sea duty and transferred to the U.S. Army for use as coastal artillery. In this capacity, the maximum range of the Mark 5 increased to , due to the greater elevation that was possible. These guns were not deployed by the US Army, and some were sold to Brazil, where they might still be in use. In Greek service, the guns removed from Lemnos were emplaced on the island of Aegina, where they helped to defend the approaches to the port of Athens. See also Weapons of comparable role, performance and era 305mm/45 Modèle 1906 French equivalent BL 12 inch Mk X naval gun British equivalent Type 41 12-inch (305 mm) /45 caliber naval gun Japanese equivalent References External links Naval guns of the United States 305 mm artillery Coastal artillery