Woops: Gallagho beat me to it
The 6 cell adapters that is used in your M6 has cells wired 2 parallel, 3 series.
The MN20 and MN21 are ~7.5V and ~6.6V bulbs, respectively.
So when loaded with 3.7V cells, you get ~11.1V to work with. As it turns out, if you look at the spec sheet for the M series lamps on LFs website, the HO-M6R is a 10.8V bulb.
BUZ from the future said:
So then why do they call it a 13V lamp?
Tactical lamps have 2 different voltage ratings.
1. The voltage rating that Joe Public can understand, Joe sees a 3V cell, sees that his flashlight takes 3 of them, does a little 2x2=4 and decides he needs a 9V lamp.
2. The actual bulb design voltage... Under the load of a bulb, primary CR123s do not actually deliver anywhere near 3.0V of potential, after losses from cell resistance, they deliver ~2.2-2.6V depending on the specific load in question. They design the bulb with this in mind. Most "9V" lamps as described in #1 above are actually ~6.6-7.6V lamps depending on how much current the bulb is expected to draw.
Now think about this- There are a number of "12V" tactical lamps out there for 4xCR123 tactical lights, after losses from resistance, most of them actually operate in the 9-10V range. Bulbs designed to run on 3xli-ion cells need to be close to an 11V design, so when designating the bulb for use with 3xli-ion cell, it would not be smart to call it an 11V, or 12V bulb, instead, you call it a 13V bulb... this way people will not start to think that any 12V tactical lamp assembly out there could potentially work with 3xli-ion cells, because it often will not work. (can blow the lamp).
