There's a tug-of-war going on in the Department of Defense over how much money can be saved by using weapon simulators. With combat aircraft costing $3-5,000 an hour to operate, anti-tank missiles going for $70,000 each and new, computer controlled machine-gun bullets priced at $25 each, there are a lot of senior defense officials looking at ever more realistic, and cheaper, weapons simulators to keep training up, and costs down. Aircraft simulators have been around for over 70 years, and even the crude, early ones proved their usefulness. Current flight simulators are expensive, and have been for several decades, sometimes costing as much as the aircraft they simulate. Currently, a warplane simulator costs from a third to half the cost of the aircraft it simulates. The simulators, however, are a lot cheaper to operate per hour (a few percent of what the real aircraft costs.) PC based combat simulators have also been used with some success. Pilots can tell when a simulator is useful and what effect it has once they fly real aircraft. 

But ground weapon simulators are a more recent phenomenon, and use a lot of the same visual and software technology that has been so successful in flight simulators. The problem is convincing the troops, and their officers. While warplane pilots can go up in their aircraft and see if the simulator is accurate, it's rather more difficult for ground combat troops to do that. Ground combat is messier and more complex than what happens in the air, and the troops feel more confident if they can fire off a lot of those $25 "smart shells" and $70,000 anti-tank missiles. The army and marines are hoping that a generation of soldiers who have played video games their entire lives will not make too much noise as more weapons training is done via simulators, rather than live fires. A larger problem is the more senior officers, who began their military careers when the first, rather crude (visually) video games appeared in the early 1980s. While these officers are impressed with the photorealistic video games (and weapons simulators) available today, many are not so sure the simulators simulate reality enough to get the troops in shape for combat.