By the time that the Ardennes offensive began on 16 December 1944, Kammler received orders from OB West (German Army Command in the West) to begin firing at the end of the month, and the first gun tube was ready for action on 30 December 1944. Two warm-up rounds were initially fired, followed by five high-explosive shells which were fired in sequence, attended by Kammler. The muzzle velocity was approximately 935 metres per second (3,070 ft/s).

The second gun tube was brought into operation on 11 January 1945 and 183 rounds in total were fired until 22 February 1945, with 44 confirmed hits in the urban area. From the 142 rounds that struck Luxembourg, total casualties were 10 dead and 35 wounded.

The nazi ww2 one is more similar to coil guns as the projectile is propelled by synchronized pulses. Rail gun is more similar to typical gun which has basically a single time pulse at the beginning (but magnetic field instead). There’s also light gas guns which have a gun power charge to move a plug that compressed a light gas like hydrogen Ina second chamber, which then bursts a membrane to then propel the projectile. Iirc sadam was doing light gas guns

Both have the same issue of excessive barrel wear. Main difference is rail guns use no explosives at all. It’s all kinetic energy. It’s insane how much of a punch they pack. My limited understanding is that’s why we have not put any in service. The go through barrels too quickly