If local governments want to ban handguns, they have to use metal detectors in many circumstances:
Tenn. Code Ann. 39-17-1359(g)
(1) Except as provided in subdivision (g)(2), nothing in this section shall authorize an entity of local government or a permittee thereof to enact or enforce a prohibition or restriction on the possession of a handgun by an enhanced handgun carry permit holder or concealed handgun carry permit holder on property owned or administered by the entity unless the following are provided at each public entrance to the property:
(A) Metal detection devices;
(B) At least one (1) law enforcement or private security officer who has been adequately trained to conduct inspections of persons entering the property by use of metal detection devices; and
(C) That each person who enters the property through the public entrance when the property is open to the public and any bag, package, and other container carried by the person is inspected by a law enforcement or private security officer described in subdivision (g)(1)(B) or an authorized representative with the authority to deny entry to the property.
(2) Subdivision (g)(1) does not apply to:
(A) Facilities that are licensed under title 33, 37, or 68;
(B) Property on which firearms are prohibited by § 39-17-1309 or § 39-17-1311(b)(1)(H)(ii);
(C) Property on which firearms are prohibited by § 39-17-1306 at all times regardless of whether judicial proceedings are in progress;
(D) Buildings that contain a law enforcement agency, as defined in § 39-13-519;
(E) Libraries; or
(F) Facilities that are licensed by the department of human services, under title 71, chapter 3, part 5, and administer a Head Start program.