Two gunmakers who challenged Congress' authority to ban the manufacture, sale and possession of semiautomatic assault weapons lost a Supreme Court appeal Monday. The court, without comment, rejected an appeal that said Congress exceeded its power to regulate interstate commerce when it outlawed such weapons in 1994. The 1994 law, an amendment to the Gun Control Act of 1968, defines semiautomatic assault weapons to include a list of specified firearms and ``copies or duplicates of the firearms in any caliber.'' Navegar Inc. and Penn Arms Inc. challenged the federal ban in 1995. Florida-based Navegar, doing business as Intratec, manufactures two...