When Clinton was Commander in chief, he either signed a bill or made an executive order restricting carrying firearms on military installations. I don't remember the details, but this was sited as one of the reasons the soldiers were unable to defend themselves against the shooter on Fort Hood.
I don't know about the other services, but the Air Force has always been a bit strange about personal weapons, before Clinton and at least since I joined in 1973. Single personnel living in the barracks were expected to have their firearms stored in the armory but married personnel could keep their weapons in their quarters on base. I once asked a security cop about the crime on base and he said crime was higher in family quarters than it was in the barracks because there was always someone around the barracks but family quarters were often unoccupied during the day. It wasn't until a few months ago that the base exchange on Fairchild started selling firearms and ammo. I bought a handgun there, paid for it at the counter and then the salesman carried the firearm as he escorted me out the door to the parking lot. I was then expected to drive off the base and never have a firearm in my vehicle when I'm on base.
A loaded KC135 tanker holds more fuel than any of the jets that hit the world Trade Center, yet the pilots driving these "bombs" aren't allowed to open carry in the base exchange or commissary. Same situation for aircrews on other bases where they are entrusted with nuclear weapons, 20mm Gatling guns, laser guided bombs, .. well you get the idea.