While the possibilities of railguns on U.S Navy ships tantalize, the MK 45 5-inch gun continues to soldier on. BAE Systems, which has been involved in the development of railguns, recently released a video showing the capabilities of the MK 45. The 5-inch gun provides naval surface fire support for the Navy and nine other international navies at a range of 20 nautical miles. BAE Systems touts the MK 45’s installation on more than 240 ships worldwide.