I had the opportunity to proof read the SOPMOD manual edited by a good friend... I wasn't in the military at the time, but I know Mike had a problem getting the visible white light to be accepted for the SOPMOD program... how many white lights were on M4s prior to SOPMOD?
the GI one I have houses a Surefire P6 with a rail mount that fits on the barrel between the legs of the fixed sight tower.