Black River Manufacturing Benelli M4 Bolt Release Black. The bolt release is made from solid bar stock 4140 steel. Specifications for Black River Manufacturing Benelli M4 Bolt Release: Manufacturer: Black River Manufacturing Fabric/Material: 4140 Steel Color: Black Gun Make: Benelli Gun Model: Benelli M4 Gun Type: Shotgun Package Contents: Black River Manufacturing Benelli M4 Bolt Release Mounting hardware What firearm models does the manufacturer say Black River Manufacturing Benelli M4 Bolt Release is compatible with? The manufacturer suggests that Black River Manufacturing Benelli M4 Bolt Release is compatible with Benelli M4Black River Manufacturing BRBBR: Benelli M4 Bolt Release Black