An assembly of a barrel adaptor and a hammer bit, and components thereof, for use with a hydraulic hammer. The barrel adaptor is coupled about the hammer bit by means of a pin, and includes a cylindrical body, a ledge formed between an upper segment and a lower segment of the cylindrical body, and a pair of apertures extending through opposing sides of the cylindrical body and aligned with a keyway of the hammer bit, through which the pin extends in coupling. A sleeve is movably secured about a portion of the upper segment of the cylindrical body. Affixed within the bottom of the cylindrical body are one or more steel plates, and at a distal end a nosepiece, with a tooth removably affixed to the nosepiece.