I guess I am sounding way too harsh on my modded M4, trust me I always loved my Devastator. Love the size and shape of it and it does throw really very well.
Going from the stock M4 HO bulb rated at 350 lumens to this HO-M6R rated at 700 lumens I guess I expected a much brighter light not just a bit brighter, know what I mean?
Maybe since I have the AW soft start clicky installed I will try a Surefire MN21 with this Leef body and see how it goes, hopefully not poof .
As a side note does any store sell extra Surefire M4 heads without the other parts?
Oh ... one other thing I just thought of...
I've noticed, personally, that if I were to take 2 lights, of equal output, but one large, and the other very small, the small one "seems" brighter to me, it's all in my head of course, but it has to do with the concept of expectation. You've moved to a larger host size, so the expectation has risen with it to some degree, so when you didn't see a massive leap in output, it was disappointing.
I did learn one valuable thing, Lumens factory make nice bulbs but sure do get creative on the lumens ratings.
So I got a leef 3x18650 body with a HO-M6R bulb, 3 fresh 18650 batts. Put it all together with AW's soft start clicky go to turn it on and I a totally unimpressed.
I think stock m4 with the higher output bulb was brighter than this setup.