Tenn. Code § 4-54-104
A personal firearm, a firearm accessory or ammunition that is manufactured commercially or privately in this state and that remains within the borders of this state is not subject to federal law or federal regulation, including registration, under the authority of congress to regulate interstate commerce. It is declared by the legislature that those items have not traveled in interstate commerce. This section applies to a firearm, a firearm accessory or ammunition that is manufactured in this state from basic materials and that can be manufactured without the inclusion of any significant parts imported into this state. Generic and insignificant parts that have other manufacturing or consumer product applications are not firearms, firearms accessories or ammunition, and their importation into this state and incorporation into a firearm, a firearm accessory or ammunition manufactured in this state does not subject the firearm, firearm accessory or ammunition to federal regulation. It is declared by the legislature that basic materials, such as unmachined steel and unshaped wood, are not firearms, firearms accessories or ammunition and are not subject to congressional authority to regulate firearms, firearms accessories and ammunition under interstate commerce as if they were actually firearms, firearms accessories or ammunition. The authority of congress to regulate interstate commerce in basic materials does not include authority to regulate firearms, firearms accessories and ammunition made in this state from those materials. Firearms accessories that are imported into this state from another state and that are subject to federal regulation as being in interstate commerce do not subject a firearm to federal regulation under interstate commerce because they are attached to or used in conjunction with a firearm in this state.
T.C.A. § 4-54-104