USN abandoned it, due to poor anticipated utility.
Lack of electrical generation or distribution available with older ships. Zumwalt Class probable destination.
The rail-gun projectiles combined with advanced powder guns, such as Naval five-inch and/or 155mm army artillery, deliver about half to two-thirds of the desired capability.
The development of guided rounds may compensate for the ranging issues of the Combustion-Light-Gas-Guns, which preceded development of electric rail-guns. CLGG had a capability of 200 NM, but suffered inconsistent performance operating with pure ballistic rounds.
USAF abandoned the laser.
What else is in development?