The U.S. Coast Guard is doing something unusual, it is buying a weapon not used by the U.S. Navy. Traditionally, the Coast Guard equipped it's ships with weapons in the navy inventory, and let the navy supply system handle ammunition and spare parts. But for the Coast Guard's new "National Security Cutters," it is buying a 57mm gun not used by the navy. The Swedish designed EX-57 Mk 3 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 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 may use this weapon as well, as some of the proposals for the new LCS (Littoral Combat Ships) ships include a 57mm gun. The Coast Guard uses the 57mm gun for warning shots, or stopping (or destroying) small boats. For a long time, Coast Guard cutters carried a 76mm gun. But this proved to be too large for the targets typically encountered. The LCS also expects to be dealing with small enemy ships, something that a 57mm shell could more effectively handle.