3. "Firearm" means (a) any pistol or revolver; or (b) a shotgun having
one or more barrels less than eighteen inches in length; or (c) a rifle
having one or more barrels less than sixteen inches in length; or (d)
any weapon made from a shotgun or rifle whether by alteration,
modification, or otherwise if such weapon as altered, modified, or
otherwise has an overall length of less than twenty-six inches; or (e)
an assault weapon. For the purpose of this subdivision the length of the
barrel on a shotgun or rifle shall be determined by measuring the
distance between the muzzle and the face of the bolt, breech, or
breechlock when closed and when the shotgun or rifle is cocked; the
overall length of a weapon made from a shotgun or rifle is the distance
between the extreme ends of the weapon measured along a line parallel to
the center line of the bore. Firearm does not include an antique
firearm.