It's all about terminology...
I don't think you're asking the right question -
SureFire uses Lamp Assemblies rather than bare bulbs.
Strickly speaking, yes, the M3 and M3T
bulbs are compatible since they are the same. The M3 and M3T Lamp Assemblies are not compatible.
The M3's Lamp Assemblies are the MN10 and MN11.
The M3T's Lamp Assemblies are the MN15 and MN16.
The MN10 and MN15 have the same bulb (rated as 125 lumen output / 60 minute runtime)
The MN11 and MN16 have the same bulb (rated as 225 lumen output / 20 minute runtime)
TurboHead Lamp Assemblies (such as the MN15 & MN16) have a longer neck compared to the M3's Lamp Assemblies:
MN11 on the left
MN16 on the right (note that this is the old version. The current version is black with it's model laser etched to identify it)
This is what happens when you try to put a TurboHead Lamp Assembly in an M3 bezel:
It is too long.
Again, I don't think you're asking the right question.
Yes, the MN15 and MN16 Lamp Assemblies fit in the KT TurboHead since they are TurboHead Lamp Assemblies.
However, the 'KT' TurboHead is
not the same as the Millennium TurboHead.
A TurboHead Kit is the TurboHead bezel, adapter collar (if required) and Lamp Assembly). The kits are referred to by number.
A 'KT' TurboHead is the TurboHead bezel used by three of the kits (KT1/KT2/KT5)
These are the 'KT' TurboHeads:
(Note that the KT2 currently comes with the MN15 rather than N2 Lamp Assembly)
KT1 and KT2 are the same except for the Lamp Assembly. They feature the KT TurboHead and adapter collar for the standard body SureFires (such as the 6P/G3 etc)
KT3 is specifically for the 9AN.
KT5 is the KT TurboHead & an adapter collar for the 8AX/8NX/L7 bodies.
KT4 is the TurboHead Kit for the three-SF123A Millennium Series models. It comes with both the MN15 and MN16 Lamp Assemblies:
I hope I've been able to explain and demonstrate the differences?
Anyway, does your recently obtained M3 come with both the MN10 and the MN11 High Output Lamp Assembly?
If it does all you need is a fresh set of SureFire SF123A or Duracell DL132A batteries to enjoy the MN11's higher output!
The SureFire TurboHead bezels change the beam (the distribution or intensity of light). The TurboHead creates a far more intense beam better suited to illuminating targets further away and is more ideal for outdoor use.
This is the M3 bezel with MN11 Lamp Assembly:
This is the Millennium TurboHead bezel with the MN16 Lamp Assembly:
In my opinion the TurboHead is a fantastic version of the M3. I find myself using the M3T far more often then the M3.
Al