So, I’m looking at putting a two CR123 light on my carbine as I would like more throw than my current 1 CR123 Arisaka M300 “clone”. I’ve pretty much narrowed my choices to the Surefire M600U and the Arisaka/Malkoff M600 “clone” with the super thrower head. Now I believe that Will from Arisaka has previously said that he actually prefers the M600U for the most part due to battery life. I see that the Arisaka/Malkoff lists a battery life of about 15-20 minutes which seems quite short. I believe I also have read things indicating that Malkoff measures battery life differently and perhaps more honestly, if you could say that, than other flashlight makers. I guess my question is, has anyone compared these two side by side for battery life? I’m quite satisfied with the M600U on my duty rifle, but it’s issued. If I can save $100, get an equally or more rugged light and have 75% or more of the battery life than I think that would be the way to go. On the other hand, if they measure battery life the same way and one is 15 minutes and the other is an hour than I’ll probably have to save my pennies. Thanks for any available guidance.