SureFire M6LT Guardian Review

The SureFire M6LT Guardian is the latest revision of the original M6 and now comes driven by an LED instead of a filament bulb. Up the front, the head has a crenelated bezel. The crenelations are shallow which serve to light shining through if the M6LT is left switched on and placed head-down. Just behind the bezel is a tempered glass lens which protects the optics used to focus the light from the LED. The M6LT uses total internal reflection (TIR) optics, similar to many of their other tactical flashlight models. Externally, the head has a pretty clean conical design with some etched grooves for aesthetics and a series of cooling fins which help dissipate heat for the high output LED. The head is adhered and sealed to the battery tube and is not meant to be removed.

The entire light is coated and finished in an olive/khaki colored Type III anodizing. Incidentally, the color of the anodizing isn’t consistent with the head having a less saturated color tone compared to the rest of the body. Being powered by 6 CR123 batteries, the battery tube has a nice size to it without being too wide and feels very comfortable when held in hand. The contours machined along the battery tube, while may look somewhat aggressive, actually fits the contours of the fingers really well and adds to the comfort. Inside, the SureFire M6LT employs a battery magazine to hold the 6x CR123 batteries which power the M6LT. While using magazines is a good idea, the design of the one in the SureFire M6LT is really bad and introduces multiple issues during use. Firstly, the CR123 batteries are held very tight when installed in the magazine which makes removing them from the magazine a real hassle which isn’t helped by the bracket structure. Secondly, loading the batteries into the magazine also poses issues because there is nothing which guides/holds the batteries in place which can cause the batteries get stuck in the mid section of the magazine. Threads between the battery tube and tail cap are cleanly machined, but are not square-cut like some of the earlier SureFire models. Nonetheless, they are thick and should hold up well to heavy use. Just behind the threads is a thick rubber o-ring which provides a tight moisture seal. When screwing on the tail cap, you’ll definitely feel the resistance between the rubber o-ring and tail cap. The switching mechanism employed by the M6LT is a combination of a momentary forward push button, and twist for constant on. It can be locked out by unscrewing the tail cap about 1.5 turns. The push button mechanism is totally silent and has short travel with average resistance. The rubber switch cap protrudes out the tail end which means the SureFire M6LT isn’t able to tail stand. There is also a rotating lanyard attachment loop which sits behind the rubber o-ring.

The user interface of the SureFire M6LT is really simple and straight forward. It only has one output level, a very bright 900 (advertised) lumens. The beam profile has a very specific form, throwing a very narrow hot spot with and almost non-existant (relative to the hot spot) spill beam region. There are some ring-shaped artifacts in the beam profile as expected from optics-based lights, though this really doesn’t affect practical usage. Beam tint is almost a neutral white with no noticeable warm or cool tint. SureFire are known for accurately rating their flashlights’ output without over inflating their numbers. In fact, the review sample tested with an output of 938 lumens. Unfortunately, this high output level is maintained very briefly, even with active cooling applied to the light. In fact, the SureFire M6LT’s output dips quickly to 84% after just 1 minute and stays around the 80% mark for most of its regulated run time. Speaking of which, run time is another area where the SureFire  M6LT falls short. The packaging advertises the M6LT as providing a run time of 4 hours. As can be plainly seen from the run time graph below, output is only 3% by the time it reaches the 4-hours mark. The SureFire website on the other hand, states the M6LT as having a 3.2-hour tactical run time. Do note that SureFire considers tactical run time as long as the light stays above 50 lumens. While this may be true for the M6LT (actually, output is about 46 lumens at the 3.2-hour mark), I doubt most users would appreciated 50 lumens “tactical” considering the initial high output of 900+ lumens. I feel SureFire should really consider revising their definition of tactical output, perhaps relative to the different outputs of their various models since user expectations also vary depending on the flashlight model. All this and considering the M6LT runs on 6x CR123 makes for a really expensive tactical illumination solutions to run.

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