Muscatatuck lookout

As an avid military frequency listener I and another friend have been hearing OV-10 aircraft above Jefferson Proving Grounds (JPG) on 343.00 MHZ. also many pilots with heavy accents. These OV-10 aircraft seem to be flying above Muscatatuck. Anyone have more info ?

Aircraft OV-10 photo from:
http://www.tstonramp.com/