Electromagnetic Blunderbuss
The predecessor of modern railguns and Gauss rifles, the Electromagnetic Blunderbuss exchanges precision for brutality. It fires a burst of inaccurate but deadly metallic projectiles, propelled by powerful electromagnets.
Some models also included a spring-loaded bayonet with a slender blade mounted above the barrel. On releasing the catch, the bayonet flipped forward and locked into position.
The width of the barrel, inconsistencies in the shape of the shot, and the uneven characteristics of the magnetic fields all guarantee serious scatter.
This means that the blunderbuss is virtually useless at long range, but also that it's a wonderful area weapon at shorter range.
If you don't have standard shot, you can load a blunderbuss with just about any material that interacts with a magnetic field and can be crammed down the barrel. This can be rocks with high metal content, nails, rusty scraps of iron, etc.