The U.S. Navy Quietly Tested Mach 3 Heavy Gun Shells That Could Revolutionize Surface Warfare

The U.S. Navy, without fanfare or notice, tested a new weapon last summer that could revolutionize surface warfare. The hyper velocity projectile (HVP) is a Mach 3 shell fired from existing guns on cruisers and destroyers. A guided projectile, HVP can drop high explosives on enemies on the ground up to three times as far as conventional ship gun ammo with a high rate of precision. It can also intercept incoming anti-ship missiles, providing an economical alternative to increasingly expensive anti-missile interceptors.

According to USNI News, the guided missile destroyer USS Dewey fired 20 new HVP projectiles during the 2018 Rim of the Pacific (RIMPAC) exercises. Although the test was unclassified, it was not reported at the time by the U.S. Navy. It was the first known use of HVPs at sea by a warship.

Large surface combatants in the U.S. Navy all carry the Mk.45 5-inch (127mm) Naval Gun System. Unlike railguns, these are chemical energy guns that use gunpowder to launch projectiles, a basic technology hundreds of years old. Guided missile cruisers of the Ticonderoga-class carry two Mk.45 guns, while guided missile destroyers of the Arleigh Burke-class carry one. These guns are typically used for shore bombardment, softening up enemy defenses before an amphibious assault, although in a pinch they could be unleashed against enemy surface ships and incoming aerial threats.

The unguided nature of these rounds, however, makes them less accurate than missiles. Amphibious assaults are also extremely rare, making the guns increasingly difficult to justify in the age of fast-moving missiles.