Firearms and Ammunition - As enacted, prohibits the purchase or possession of a firearm by a person under 25 if the person was previously adjudicated delinquent for an act that, if committed by an adult, would have constituted certain offenses; allows the TBI access to juvenile court records for the limited purpose of performing a background check prior to the transfer of a firearm or to determine eligibility for a handgun carry permit pursuant to existing law. - Amends TCA Title 18; Title 37 and Title 39.