The USS Zumwalt (DDG-1000) is the US Navy’s latest warship, commissioned just last month—and it comes with the biggest guns the Navy has deployed since the twilight of the battleships. But it turns out the Zumwalt's guns won’t be getting much of a workout any time soon, aside from acceptance testing. That’s because the special projectiles they were intended to fire are so expensive that the Navy has canceled its order.

Back when it was originally conceived, the Zumwalt was supposed to be the modern-day incarnation of the big-gunned cruisers and battleships that once provided fire support for Marines storming hostile beaches. This ability to lob devastating volleys of powerful explosive shells deep inland to take out hardened enemy positions, weapons, and infrastructure was lost after the Gulf War’s end, when the last of the Iowa-class battleships were retired. To bring it back, the Zumwalt’s design included a new gun, the Advanced Gun System (AGS). As we described it in a story two years ago:

The automated AGS can fire 10 rocket-assisted, precision-guided projectiles per minute at targets over 100 miles away. Those projectiles use GPS and inertial guidance to improve the gun’s accuracy to a 50 meter (164 feet) circle of probable error—meaning that half of its GPS-guided shells will fall within that distance from the target.

The projectile responsible for that accuracy—something far too complex to just be called a "shell" or "bullet"—is the Long Range Land-Attack Projectile (LRLAP). Each projectile has precision guidance provided by internal global positioning and inertial sensors, and bursts of LRLAPs could in theory be fired over a minute following different ballistic trajectories that cause them to land all at the same time.

Lockheed Martin won the competition to produce the LRLAPs, and the company described their capabilities thusly:

155mm LRLAP provides single strike lethality against a wide range of targets, with three times the lethality of traditional 5-inch naval ballistic rounds—and because it is guided, fewer rounds can produce similar or more lethal effects at less cost. LRLAP has the capability to guide multiple rounds launched from the same gun to strike single or multiple targets simultaneously, maximizing lethal effects.

The "less cost" part, however, turned out to be a pipe dream. With the reduction of the Zumwalt class to a total of three ships, the corresponding reduction in requirements for LRLAP production raised the production costs just as the price of the ships they would be deployed to soared. Defense News reports that the Navy is canceling production of the LRLAP because of an $800,000-per-shot price tag—more than 10 times the original projected cost. By comparison, the nuclear-capable Tomahawk cruise missile costs approximately $1 million per shot, while the M712 Copperhead laser-guided 155-millimeter projectile and M982 Excalibur GPS-guided rounds cost less than $70,000 per shot. Traditional Navy 5-inch shells cost no more than a few hundred dollars each.

In theory, the Army's Copperhead or Excalibur rounds could be adapted to the AGS, because the gun is the same bore-size and is essentially a sea-based howitzer—it fires at a higher angle than previous naval guns and is designed strictly for firing at land targets. The Excalibur has been used successfully in combats against targets more than 20 miles away. The Navy is reportedly looking at the Excalibur as one option, as well as the Hyper Velocity Projectile (HVP)—a projectile being developed by BAE Systems under contract with the Office of Naval Research for use both in traditional powder-fired guns and a future Navy electromagnetic railgun system.

In the long run, the HVP will likely win out—that is, if the Zumwalt is successfully fitted with a railgun. The ship’s all-electric design was created with the intention of being compatible with high-energy weapons (like railguns) once they're generally available, and the HVP would be the obvious next step. HVP is also being developed for existing naval guns and howitzers.