The Blunderbuss is an antique black powder single-shot antique firearm.
What's interesting about the Blunderbuss is that it could fire virtually anything that could fit in the barrel, other than lead shot. This included rocks, glass and other projectiles. Essentially, the Blunderbuss was the forerunner of the modern shotgun, but with a flint lock action.
Burt Gummer uses a Blunderbuss to kill the last remaining Shrieker in the episode Shriek & Destroy when nothing else is available.