The day after his birthday last week, George J. Hennard armed himself with two semiautomatic pistols that held a total of 32 bullets, stuffed his pockets with extra ammunition, then drove his pickup truck through the window of lunchtime-crowded Luby's cafeteria in Killeen, Tex., and began shooting people. Ten minutes, many screams and maybe a hundred shots later, 23 people lay dead -- Mr. Hennard among them, a suicide -- and 23 others were injured.