Your comment made me think about something.
I inserted a link showing the SINCGARS,
http://en.wikipedia.org/wiki/SINCGARS , radios they use now. Since they frequency hop similar to a trunked system, with other digital and encryption stuff to go along with that, it is very hard to scan. (Seems they made them that way to keep them from being jammed and monitered by the bad guys.)
But on Live Fire Ranges, like out in the west desert, you are always on a static frequency. Even when you are doing tactical training; when you move to a range to shoot you always switched to the frequency for that range, since typically those frequencies were permantly assigned to the range. Some of the larger range complexes I went on had several frequencies assigned for various things. But there was only one live fire frequency.
It would be of interest to see if that frequency stayed active with the same type of traffic.