6. The Vandenburg Volley Gun
While the Vandenburg volley gun was multi-barreled, able to fire off from 451 barrels, each one had to be individually loaded after each use. This created a highly time-consuming task, which would’ve been an absolute disaster for anyone on the battlefield.
Designed in the 1860s by General Origen Vandenburg, the volley gun was reasonably accurate but had little else going for it. It was heavy to carry and hard to clean, adding to the extremely slow rate of fire that could leave the troops exposed.
The Vandenburg volley gun was rejected by both the US military and Britain. Somehow, General Vandenburg was able to sell a few to the Confederacy.