Civilians who are caught carrying concealed handguns on base get a quick trip to the federal magistrate. The magistrate will set hearing date.
You can't legally carry a concealed handgun onto an Army base for the same reason you can't legally carry a concealed handgun into a federal court house or post office. Guns are forbidden in the VA hospital parking lot in OK City.
The law governing the carry of a weapon on federal property is Title 18, Chapter 44, § 930 of the US Code.