A suppressor for a firearm is provided, wherein the suppressor can be selectively oriented relative to the firearm. The suppressor has an elongate body, a piston assembly and a cam assembly. A piston of the piston assembly can be fixedly attached to the barrel of a firearm. An indexing ring is radially fixed relative to the piston. The cam lever is selectively movable between a second position, in which the indexing ring is fixed relative to the elongate body, and a first position, in which the indexing ring can rotate relative to the elongate body.