Extended Range Guided Munition

The Extended Range Guided Munition was a precision guided rocket-assisted 5-inch (127 mm) artillery shell development by Raytheon for the U.S. Navy. The program was cancelled in March 2008 after twelve years of development and over 600 million dollars in funding. The developmental round was designated EX 171. ERGM consisted of three major subsections; propulsion (rocket motor), warhead, and Guidance, Navigation and Control section. ERGM is fired from the 5 inch 62 Caliber Mark 45 gun Mod 4 at which point the fins deploy, rocket motor would ignite and lift the munition to at least 80,000 feet (24 km) when the canards would deploy and guide the ERGM to the target based on GPS guidance. It was to be used on Arleigh Burke class destroyers (hulls DDG-51 through 112).

Despite the long development time the ERGM never worked as reliably as the older but significantly less expensive laser guided M712 Copperhead. During development, the ERGM failed several tests in which the tail fins failed to deploy at launch, rocket motors did not ignite or the electronic components did not survive the stress of being shot from a deck gun. Rising cost was another likely factor in cancellation. The unit cost of the shell more than tripled, from $45,000 in 1997 to $191,000 by 2006, reducing the projected buy from 8,500 to about 3,150 (in contrast the Copperhead average unit production price was about $30,000). BTERM is another U.S. Navy developmental round that includes GPS guidance in an artillery shell; it too was terminated in 2008 after 4+ years of development by ATK. XM982 Excalibur is a U.S. Army round in development.

Italy has developed a long range 127mm shell, called the Vulcano, which works differently from ERGM and does not use a rocket motor. Instead it uses a discarding sabot and a steerable sub-munition shaped like a small rocket. The key advantage of the Vulcano is that it can be used on conventional guns without distorting the gun barrels, as happened with the ERGM and BTERM. Vulcano, produced by the firm Oto Melara, part of the Finmeccanica group, has the sponsorship of the Italian Navy. Its electronics and guidance system are similar to ERGM and the munition has steerable canards. The reported range of these projectiles is almost as good as the ERGM. The Vulcano meets the U.S. Navy and U.S. Marine's requirement for an extended range munition that can support Marine operations, although the U.S. Navy and Marines have yet to evaluate the Vulcano system.