For nearly ten years, the U.S. Navy has been trying to perfect a long range shell for the five inch gun found on all of their destroyers and cruisers. The Mark 171 ERGM (Extended Range Guided Munition) is an oversize shell (61 inches long and 110 pounds, 2.3 times the size of the normal shell) that uses a rocket booster and GPS guidance to hit targets 110 kilometers away. The normal range of five inch shells is about 23 kilometers. But the ERGM has limitations, like a lower rate of fire (10 shells per minute, versus 20 for normal shells) because of the greater heat and stress the ERGM shell puts on the barrel and loading mechanism.) The ERGM shell would carry 72 nine ounce submunitions, similar to those used in army shells and rockets. The gunners can program the shell to disperse the submunitions to fall into circular areas from 20 to 100 meters in diameter. New destroyers are equipped with a five inch gun modified to handle the ERGM, and most existing ships will have their five inch guns modified to handle ERGM. But the new shell was supposed to enter service in 2002. Now it is scheduled for service in 2005. And there's another problem, the people who originally asked for the ERGM, the Marines, are not sure they'll be needing it for fire support. The Marines see themselves doing more missions deeper inland, beyond the 110 kilometer range of the ERGM. Nevertheless, it is an impressive weapon, and testing continues. When problems are encountered, they are fixed and progress has been steady, if behind schedule. South Korea and Denmark have bought five inch guns modified for ERGM use.