The U.S. Army's new self-propelled
artillery (the 155mm NLOS-C) is designed to last for 20 years. During that
time, it is expected to travel 1,200 kilometers, and fire 250 shells a year, all
in training. If there is a war, the system gets used a lot more heavily, and
might easily be worn out or destroyed after a year in a combat zone. This is
typical, as most weapons systems never see combat, and are built to deal with
the rigors of the battlefield, as well as decades of light peacetime use.
not to say that NLOS-C's will be thrown out after twenty years. They will
probably be refurbished so that they can serve another decade or more. That has
happened to some of the current M-109 self-propelled 155mm guns, which first
appeared in the early 1960s.