Poor performance - SureFire M500A Car15 / M4 Carbine Tactical Dedicated Forend Flashlight

purchased for and installed on M4A3 Bushmaster, for use in urban/suburban patrol setting; installation was a snap; controls well placed and easy to learn; battery life, with the smaller output lamp, was under twenyy minutes of really usable light, and that was fairly intermittent use; this light didn't make it ten minutes into a building clearance scenario before the output began to "yellow"; new batteries inserted, same results; not acceptable in a true tactical situation, but it LOOKS GOOD. I will contact SureFire factory for their response, and will update my review if there is a problem with my specific device.
Pros: excellent ergonomics, easy to install, designed & built well
Cons: extremely poor battery life

This review was written in the old system and had content requirements that are different than reviews written today.