(note that the actual principles involved in them are used in real things, but mostly for accelerating things along rail systems, not as guns or cannons)
[Legendary - Success]: Schwerer Gustav, but you don't shoot from it, you shoot it.
I truncated that down a bit because it was already getting a bit too wordy, so I skipped the examples. That would be things like some roller coasters using electromagnetic launch systems over conventional chainlift hills, aircraft catapults on carriers to get them up to speed fast enough to take off, some trains use them for propulsion, etc. It's a really good way of making a big fixed system push things along quickly for definitions of "quickly" that include accelerations humans can comfortably survive, it's just not very good at making a small and portable system for launching projectiles very fast at a speed that a human on the other end of the equation wouldn't comfortably survive.
I truncated that down a bit because it was already getting a bit too wordy, so I skipped the examples. That would be things like some roller coasters using electromagnetic launch systems over conventional chainlift hills, aircraft catapults on carriers to get them up to speed fast enough to take off, some trains use them for propulsion, etc. It's a really good way of making a big fixed system push things along quickly for definitions of "quickly" that include accelerations humans can comfortably survive, it's just not very good at making a small and portable system for launching projectiles very fast at a speed that a human on the other end of the equation wouldn't comfortably survive.
To be fair if I'm launching the actual schwerer gustav at things I don't think "human that rides on it could survive" is high on the priority list