a gun that is used at a short range, characterized by a flared muzzle and wide bore for loading the weapon as well as a short barrel;
e.g. He was armed with a blunderbuss and a sword.
(noun)
some action that is imprecise and lacking in subtlety, a method or manner of doing something that has these qualities, or a person who tends to be careless and make foolish errors;
e.g. The policy may be effective, but it is a blunderbuss that is too extreme. She is a blunderbuss who cannot be trusted with this task.