Get Some!
 

That is a cool toy.

Why was a gun like that ever built? Just because someone could? What was the designed purpose of that thing?

Carl Spackler has one on order.

Gee, and my biggest rifle only shoots projectiles 1/3 that size.

Still, it seems like the cases don't have a whole lot powder behind them (relatively), and the muzzle velocity is only 2100 fps. The rifle could probably stand to have a better muzzle break as well. What is the caliber? 25mm?