Hello,
Are you running a MOD?
Single player or multiplayer?
If it is a MOD the person who had made the MOD is not allocating enough resource to the weapons in the DefaultCore.
I usually add approximately 5% to what is required.
If you run a single player game you can change this, but if you are running in multiplayer you cant.
F9thCenturus is 100% correct just visit a planet or base to visually re-charge the weapon. Though in reality there is not a problem with the weapon, but it good to re-charge your systems anyway.
Worfy