Pancor Jackhammer
The Pancor Corporation Jackhammer is a 12-gauge, blow-forward gas-operated bullpup automatic shotgun designed in 1984 and patented in 1987. Only three working prototypes of the Jackhammer were built, but despite notable interest, legal and financial issues meant the Jackhammer never entered production, though it was notably popular as a prop weapon in films, television shows, and video games in the 1990s and 2000s, owing to its futuristic design and unusual operation.