Millions of substandard bolts and nuts have been used in everything from military equipment and weapons to the space shuttle and commercial trucks, a congressional panel said. A two-year investigation by the investigations subcommittee of the House Energy and Commerce Committee uncovered millions of substandard bolts, nuts and screws--many of them imported from Japan. The problem could have wide-ranging effects. For example, 1,200 M-60 tanks were removed from Army service for at least two months while defective bolts in the gun mounts were replaced, and substandard fasteners were sold to the Navy for use on both submarines and aircraft carrier jet catapult systems, the panel said. The fasteners contained more boron and less carbon than specified in industry standards, making them more likely to break or shear, the panel said.