Do whatever you want. They are not going to tell you whether you can or cannot open carry a long gun. Even if by some chance a cop sitting at the police station told you you could, no other cop is bound to that. As I have already written, each case is incident specific.
Well, I wasn't talking about just walking up to a beat cop and considering that authoritative.
In Austin I guess I would speak to the Chief of Police, Art Acevedo.
For DPS I suppose it would be Director Colonel Steve McCraw.
It would be nice to get some clarification from the people that set policy.