There is a bit of everything here. In Antietam lake section, climb the fire roads and then find singletrack to take down the hill. There is more singletrack on top of the mountain. A lot of the singletrack is quite rocky. There are downhill trails on the other side of the mountain.
There is a gravel lot off Angora Road from Antietam Reservoir. This is just past the intersection with Hill Road if coming from the east.
http://www.singletracks.com/item.php?c=1&i=6684