You usually won't see tactical a/c on ADS-B. 4 AH-64s at 300' well inside US airspace seems about right for routine movement. I just pulled up the US sectionals for that airspace and there isn't a defined ops area, but there are heavily travelled victor airways that the military also use in civil airspace. One leads directly to Bigg Army Airfield at Ft. Bliss in ELP.