Firearms and Ammunition - As introduced, redefines "minor" to mean a person less than 21 years of age for the purpose of determining the legal age to purchase or own a firearm, unless the person is a military service member or honorably discharged or retired veteran at which point the person may be 18 years of age or older to purchase or own a firearm; makes it a Class A misdemeanor for a minor to purchase or own a firearm or for a person to sell, loan, or gift a firearm to a person younger than 21 years of age if the person is not a military service member or veteran. - Amends TCA Title 39, Chapter 17, Part 13.