BURNISHED BY THE LOW LIGHT OF GLASS-WALLED DISPLAYS, THEY seem like ancient artifacts, but the objects here are beloved contemporary icons. One case houses the massive Smith & Wesson Model 29 wielded by Clint Eastwood's "Dirty Harry" Callahan in the 1973 film Magnum Force. In another rests the Beretta 92F used by Bruce Willis in Die Hard. All the great shoot-'em-up classics — The Bourne Identity, Pulp Fiction, The Wild Bunch — are here. This exhibit, celebrating cinema, isn't in Hollywood; it's thousands of miles away, in a museum at the headquarters of the National Rifle Association in Fairfax, Va.