You can have 2 states in the military. Your home of record state and the one you are assigned to. So, if I understand it right, you can buy in TX and MD. Not in VA unless you become a resident there and give up your TX (which I wouldn't do).
You aren't a resident of VA unless you declare it, start paying taxes, etc.
One exception to this which I know is being assigned to Ft. Campbell. ATF gives you both TN and KY in that case since the post straddles the state line.
He who dares wins.
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