Business premises. The property on which the manufacturing or importing of firearms or ammunition or the dealing in firearms is or will be conducted. A private dwelling, no part of which is open to the public, shall not be recognized as coming within the meaning of the term.
27 CFR § 478.11
When used in this part and in forms prescribed under this part, where not otherwise distinctly expressed or manifestly incompatible with the intent thereof, terms shall have the meanings ascribed in this section. Words in the plural form shall include the singular, and vice versa, and words importing the masculine gender shall include the feminine. The terms includes and including do not exclude other things not enumerated which are in the same general class or are otherwise within the scope thereof.