The Surefire 618LFG shotgun grip replacement light uses the LED 6P host, runs off of 2 CR123s with an 80lm output, but only last for 3 hours. This is just like the Original LED 6P, but has 8 hours of runtime cut off. I dont get it could someone explain please. I plan on buying this and mount it on my remington 870. I want to change the lamp assembly to the M60, is this even possible? I wonder what the run time would be like with the M60 haha.