In one aspect of the invention a buffer retaining pin is provided that comprises an elongate body. The elongate body comprises a cylindrical body portion. The elongate body has a longitudinal axis, a proximal end, and an opposite open distal end. The cylindrical body has an inner chamber in communication with the open distal end. A tooth is located at the proximal end of the elongate body. The tooth is integral with and extends from the cylindrical body such that the cylindrical body portion extends between the tooth and the open distal end. The tooth defines a top side, a left side, a right side, a front face, and a rear face. The front face of the tooth extends in a plane such that the plane of the front face intersects the longitudinal axis.