Police officers tried to help a drunk man at a subway station — and realized he was packing a bizarre-looking homemade rifle in his pants, leading to his arrest over the weekend, police sources said Monday. Melvin Montoya, 37, was found drunk inside the 149th Street–Grand Concourse station in Mott Haven around 11:45 p.m. Saturday, and cops jumped in to aid him, authorities said. That’s when they noticed a long, heavy metal object going down his leg. The officers frisked Montoya — and he allegedly reached for the crudely-made weapon, which the NYPD’s Emergency Service Unit later determined was...