The Blunderbuss is an early muzzle loading firearm, considered by some to be an early form of the shotgun. The word Blunderbuss comes from the dutch word donderbus which is derived from the words donder meaning "thunder" and bus meaning "Pipe". Therefor the Blunderbuss is a boom stick.
The Blunderbuss, for which the barrels were made of steel or brass, were loaded with shot or small lead balls, which were smaller than the diameter of the bore, and these lead balls were deadly at close range, not only from the immediate damage but also from lead poisoning caused by the embedded lead balls.
While the blunderbuss was often used by troops going into battle while the shorter blunderbuss, called a Dragon, was used by cavalry. The Dragon was so called because early versions of the pistol Blunderbuss were carved with a dragon's head around the muzzle, giving the muzzle blast the impression of a dragon breathing fire.
While not typical of fantasy games, old school firearms (used as a one shot weapon) bring an interesting element to the game. Not only do they add an element of evolution to the game it also encourages roleplaying by giving your characters something new to react to and to try to understand if they have never encountered a firearms in their lives. Are they technology? Are they magic? Are they both? The blunderbuss and Dragon also bring something else to the game: flair. A dragon carved pistol in the hands of an adept Player can create a brand new PC and style of play for that character.