§ 1. When used in this act the following words and phrases shall be construed as follows: “Pistol” shall include any pistol or revolver, and any shot gun, rifle or similar weapon with overall less than twenty-six inches, but shall not include any pistol without a magazine or any pistol or revolver designed for the use of blank cartridges only. “Machine gun” shall include any weapon which shoots automatically and any weapon which shoots more than twelve shots semi-automatically without reloading. “Firearm shall include any machine gun or pistol. . . “Crime of violence” shall mean and include any of the following crimes or an attempt to commit any of the same, viz.: murder, manslaughter, rape, mayhem, assault or battery involving grave bodily injury, robbery, burglary, and breaking and entering. “Sell” shall include let or hire, give, lend and transfer, and the word “purchase” shall include hire, accept and borrow, and the expression “purchasing” shall be construed accordingly. . .§ 4. No person shall, without a license therefor, issued as provided in section six hereof, carry a pistol in any vehicle or concealed on or about his person, except in his dwelling house or place of business or on land possessed by him, and no person shall manufacture, sell, purchase or possess a machine gun except as otherwise provided in this act. § 7. The attorney-general may issue a permit to any banking institution doing business in this state or to any public carrier who is engaged in the business of transporting mail, money, securities or other valuables, to possess and use machine guns under such regulations as the attorney general may prescribe. § 8. It shall be unlawful within this state to manufacture, sell, purchase or possess except for military or police purposes, any muffler, silencer or device for deadening or muffling the sound of a firearm when discharged.