Hey, I've been looking up my Saint Chamond rail gun, and it turns out the French used these things a lot in WWI to blow the crap out of the Bosch. It was 340mm, much heavier than the Leopold, though it's range left something to be desired. It's projectile weighed twice what the K5's did! Great googamugga!
We (the Americans) used them too when our guys got over to France. One 340 was nicknamed "Queen Elizabeth" by the American troops.
Ok, if you guys extend this to a 1/35th scale railway gun build, or just a railway gun build, I am officially in. I've always wanted to paint a vehicle
horizon bleu.