The Naval Surface Warfare Center has fired the most powerful electromagnetic railgun, sending a seven-pound bullet out at seven times the speed of sound with 10.6 megajoules of kinetic energy.

The device is part of the U.S. navy’s railgun development program. A railgun could eventually send a 40-pound slug 200 miles in six minutes–10 times the range of the navy’s current primary surface support gun, the MK45.