Nothing in sections 320.106 to 320.161 shall be construed as applying to the manufacture, storage, sale or use of signals necessary for the safe operation of railroads or other classes of public or private transportation or of illuminating devices for photographic use, nor as applying to the military or naval forces of the United States, or of this state or to peace officers, nor as prohibiting the sale or use of blank cartridges for ceremonial, theatrical, or athletic events, nor as applying to the transportation, sale or use of fireworks solely for agricultural purposes, provided^* the items sold for agricultural purposes shall be limited to those items that are legal for retail sale and use within the state of Missouri.