I can remember when any light at all from your light was considered a success. A carbide cap light was considerably more dependable...

I have had good, albeit limited experience with Nitecore 3400mh batteries

Actually you cannot trust the mfg specified capacities in many cases. Take a look at the following reviews to get an idea of some of the better models.

http://lygte-info.dk/review/batteries2012/Common18650Summary%20UK.html

Now that I've shifted slightly to the dark side and have invested in an 18650 and LED upgrade for my SF 6P, I added to it by ordering a ThruNite TN12 (neutral white). The neutral white version is supposedly 20% less out the front as cool white, so this one should max out at 840 lumen (Turbo), 296 lumen on high and 116 lumen on medium if my arithmetic is correct. The numbers advertised are for the cool-white version and are higher.

The TN-12 had good reviews on Amazon; I'll let you know how it feels and if I notice any issues once it arrives.

Russ...my older SF 6P (originally an incandescent) will not take the IMR 18650 cell that does fit in the Solar Force L2M body...

Yes, you cannot assume lights designed to fit 2 x 123a cells will accomidate an 18650 as they are slightly larger diameter. For these lights you can typically use 17670 cells, although at the cost of capacity.

-john

If you're really attached to the light you can have it bored out to accept an 18650. It's not super expensive. Or you can get a replacement body already bored out. Overready is one source but there are several others.

http://oveready.com/

I have three. All are either 2D or 3D LED MAG-LITE. My first, the one that got scratched up in the accident, is an incandescent converted to a LED.

Jeanette Isabelle

Thanks. I have a feeling the Surefire lights (6P and 6R) will stay with CR123A batteries. The batteries incoming will work in other lights already capable of taking the ever so slightly fatter 18650's.

I have a lot of affection for the 6P. Even though I have three Elzettas and a number of newer Surefires I still like my 6Ps converted to LED with Malkoff modules. They're built like a tank! Just really solid and useful. I love the lack of bells and whistles, too- all they do is light up on setting, HIGH. The lockout tailcap is great if you stow one in your pack, too...no more finding the light came on in your bag and died before you needed it.