The four-story weapon was so heavy that it needed to be disassembled in order to ride the rail car it travelled on so as to not damage the rails. It took a 500 man crew to put this thing together, and even with that many it took three full days to have it ready for firing.
What it lacked in speed it made up for in punch, though. The barrel of the Gustov Gun was nearly a yard across. This was needed for the two types of ammunition it took. There was a 10,584 lb. high explosive (HE) shell and a 16,540 lb. concrete-piercing shell.
With a maximum elevation of 48 degrees, the HE shell could hit a target 29 miles away, while the bunker-buster could nail anything within 23 miles—both with reasonable accuracy. If it did hit, the HE would leave a 30-foot deep crater while the piercing round could penetrate as much as 264 feet of reinforced concrete.
This machine never saw the end of the war, though. It was captured by the allied forces and chopped up for scrap metal.
