Firearms and Ammunition - As introduced, allows law enforcement officers to carry a firearm when under the influence of alcohol or controlled substances and certain other circumstances; deletes the prohibition on carrying firearms and other weapons on higher education campuses and in parks; prohibits the carrying of weapons in K-12 schools except by certain persons, including any person permitted to carry a firearm under federal law. - Amends TCA Title 39, Chapter 17, Part 13; Title 49, Chapter 6 and Title 55, Chapter 10.