Act not to apply in certain cases.

The provisions of this Act, in so far as they relate to verification and stamping of weights and measures, shall not apply to any weight or measure,—

1. (a) used in any factory exclusively engaged in the manufacture of any arms, ammunition or both, for the use of the Armed Forces of the Union;
2. (b) used for scientific investigation or for research;
3. (c) manufactured exclusively for export.