Mass. Gen. Laws ch. 140 § 131N
No person shall sell, offer for sale, transfer or possess any weapon, capable of discharging a bullet or shot, that is: (i) constructed in a shape that does not resemble a handgun, short-barreled rifle or short-barreled shotgun including, but not limited to, covert weapons that resemble key-chains, pens, cigarette-lighters or cigarette-packages; or (ii) not detectable as a weapon or potential weapon by x-ray machines commonly used at airports or walk-through metal detectors. Whoever violates the provisions of this section shall be punished, for a first offense, by a fine of not less than $1,000 nor more than $10,000 or by imprisonment for not less than one year nor more than ten years, or by both such fine and imprisonment, and for a second offense, by a fine of not less than $5,000 nor more than $15,000 or by imprisonment for not less than five years nor more than 15 years, or by both such fine and imprisonment.
Mass. Gen. Laws ch. 140, § 131N