Crash when missile is fired from cannon

Probably too many parts.

There's no reason to split your missile into 120 separate fuel tanks - especially when you're launching one every two seconds. Even if you only get a partial breach, the tank is going to explode and take out all the others in a chain reaction anyways.

By the way, Aluminum, while admittedly shiny, makes for a terrible fuel tank material. If you still want a shiny fuel tank, try Magnesium, Some aluminum alloy of your preference, or Boron Carbide.