The Liberator Gun
In theory, like many of the inventions on this list, the liberator gun was a good idea. Constructed from sheet metal, this gun was intended to be a one-shot wonder. A single bullet could be fired from this gun. The idea was to drop it from the air to resistance movements during WWII. But the idea lost importance when they realized a single-bullet gun doesn’t match up well against a machine gun.
The Bendy Gun
Although arms manufacturers have actually perfected this gun now, back in WWII inventions of this sort were not really successful. Its aim was to enable soldiers to shoot around corners, but it didn’t work as planned. More often than not, bullets shattered in the chamber and even destroyed the barrel. Barrels lasted not more than 300 shots.