Hi George, I tried to reproduce this, but the only time I could get a result like this is when the normals are inverted (facing inside). Please double check that, because it does look like they are partially facing inward.
All your settings should be right, because it baked the base of the tank alright. Also you can see that it does some kind of baking on the barrel and part of the turret, so I really think that your normals are messed up.
