Assuming his discharge was dishonorable. I believe that makes firearm's possession a no-no, even in Texas. But remember who was President in 1997, the one who gave a us a new term, "to get a "Lewinsky"". Even with 8 years of AWOL, it might have been a General or other less than honorable type discharge, rather than a full dishonorable.
Where did he go AWOL?