I would stop using your airbrush, and brush the black onto the figs. It could be that the paint is too thinnned or it has be applied in too much of quantity.
Also, I dont paint my panzer crew with true black, I use a blue black.You can barely tell the difference and you will not get the Zebra effect when drybrushing.
and on the last note, Have you tried spraying a dullcoat on it?
Oh, and, its not GLOSS black is it?