NATICK Massachusetts gun dealers sold more than 2,000 military-style rifles Wednesday nearly one-quarter of the total sold last year after Attorney General Maura Healey moved to bar semiautomatic rifles that have been altered slightly to evade the states assault weapons ban. The 2,251 assault rifles snapped up in a gun-buying frenzy represented a remarkable uptick from the 132 sold Tuesday and the 51 sold Monday, before Healey announced her ban.