The Blunderbuss is a ranged weapon added by Balkon's Weapon Mod. It is less advanced than the musket, but more advanced than the bow with a standard arrow. However, it is the most powerful short-range non-melee weapon.
The blunderbuss is a decent firearm, but has a few drawbacks compared to the bow and musket. The bow shoots much faster and the musket does more damage. On the other hand, the blunderbuss fires a scattershot like a shotgun, making it VERY deadly at close range. However, attacking very dangerous mobs with a blunderbuss is not advisable, as this range will probably not give you an opportunity to back off and reload before being hit. On the upside, shots are cheaper to make than the musket rounds, and the blunderbuss reloads faster.
Blunderbuss shots are relatively inexpensive to manufacture compared to musket rounds, as they use common gravel instead of iron ingots for the projectile.