Maybe I am missing something, but to my knowlede, the difference in the two platforms sight height wouldn't allow for this. Typical AR platform height for absolute cowitness is 36mm or 1.4 inches. Not 100% sure on the height of the M4 cowitness, but the Scalarworks mount I have for an Aimpoint T2, that allows for a lower 1/8th is a pretty low mount and is made exclusively for the M4. Not sure how what you want would be possible (without a completely custom setup) but I have been wrong before.