Texas law generally restricts the sale or transfer of any firearm to anyone under 18 . However, if a parent or guardian provides written consent , it may be used as an affirmative defense for transfers to minors. 2. Handguns (Pistols and Revolvers)
Minimum Age To Purchase & Possess Laws in Texas - Giffords.org
You must be at least 18 years old to purchase a long gun from a federally licensed firearms dealer (FFL). This includes popular semiautomatic rifles like AR-15s.