Democratic Maine Gov. Janet Mills said Monday she will allow one of a final pair of gun safety bills — a waiting period for gun purchases — to become law without her signature in the wake of the Lewiston mass shooting. The governor announced that she would let a 10-day period pass without signing or vetoing the 72-hour waiting period bill, allowing it to go into effect without action. The governor also said Monday she has vetoed a ban on bump stocks that would have applied to a device that can be added to a semiautomatic rifle to allow it to fire like a machine gun.