I heard there is a rail gun design made by Zeeray. It’s be useful for orbital bombardment but it would be useless if the projectile couldn’t be maneuvered. Also, you only get one shot or else it would move out of range (depending on orbit size and planet size) or you would have to reload it. Furthermore, at a speed of around 10k meters per second (according to zeeray), you wouldnt be able to adjust course that much due to relative speed. I haven’t used it yet but I must test recoil effect on orbit.