Earlier this year it looked like the U.S. Coast Guard would, for the first time, adopt a shipboard weapon that was not also used by the U.S. Navy. This was when the Coast Guard decided to arm its new ships with the Swedish designed 57mm Mk 3 gun. This weapon is already in use by the Canadian Navy and 14 other countries. The gun has a 11.2 foot long barrel, with a life of about 4,000 rounds. The gun can fire nearly four rounds a second. It uses a 13.4 pound round, which produces a 5.3 pound shell. The turret carries 120 rounds, with another 1,000 rounds in the magazine. The usual max range is 14 kilometers. The Mk 3 has been in use since 1998, but the Mk 1 first entered service in 1966. The U.S. Navy will call this weapon the Mk 110 and will use it on its new DD(X) destroyers. The new destroyer will also have a 155-mm (six inch) Advanced Gun System (AGS). The 57mm weapon will be used for smaller naval threats, while the AGS will mainly be for supporting troops ashore. Previously, the navy had used a 127mm (five inch) gun on its destroyers. Six inch (155mm) guns had rarely been used on destroyers, and were often found on cruisers. But destroyers built in the last three decades have been the same size as World War II cruisers mounting six inch guns.