Sixty people crowded last week into a small room at the Bayonne police firing range to witness smart gun technology.  Donald B. Sebastian, senior vice president of research and development at NJIT, stood near an oversized screen displaying a real-time video of an NJIT policeman shooting an experimental handgun in an adjacent indoor range. Twenty electronic computerized sensors embedded in the gun’s grip distinguished known from unknown users. “We’ve only just begun and we’re pleased to say that we’re getting 90 percent reliability when scanning users,” said Sebastian.