THE SHOWDOWN WAS SURPRISINGLY LOPSIDED, the outcome totally unexpected. The sure-fire bill to grant the gun industry blanket immunity from lawsuits sputtered and finally failed in the U.S. Senate last week. Republicans had more than enough votes to pass the measure, but neither they nor the National Rifle Association had counted on being outmaneuvered by Democrats who managed to attach two sensible amendments to the bill. Rather than accept these riders, Republicans simply killed the bill.