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.
To take advantage of the rail guns extreme range you need a stable platform that can compensate for roll and pitch. The USN hasn’t solved this yet. Long way to go.
“CLGG had a capability of 200 NM, but suffered inconsistent performance operating with pure ballistic rounds.”
All purely ballistic “guns” suffer from the same shortcoming.
How to hit a moving target you cannot see, and which may zag at 30deg instead of zig at 15deg. AND the guided rounds are too small to take out the target when they do hit.
It would be foolish to retool a fleet around such a weapon.