Notes/Observations - SureFire's Scout lights have become one of the most popular weapon lights since I first featured them on this website in 2005. Back then, the KL4 head that came with the M600A put out 65 lumens. LED flashlight technology sure has come a long way since then. 1500 lumens seems like a lot of light, but it's not the only number that's important especially if you're outside and want to illuminate a target some distance away. I've never really had the issue of being 'blinded by too much light' indoors; even with the X300U pistol lights. As long as it's not accidentally activated on a white door right in front, the M600DF just lights up rooms and long hallways brilliantly.

Given that this light is capable of being used at longer distances, I tried it outdoors to test its throw using a couple of other lights I had on hand - my X300U-A with 600 lumens (I use the X300U on a couple of my rifles because of it's good throw. I don't have the 1000 lumen X300U-B) and the Olight M2R Warrior Flashlight which is rated at 1500 lumens as well. Throw is based on intensity (candela) while total light output is lumens. It's the intensity of the focused light at a given distance that determines how far it can illuminate an object. As expected, I found the intensity/throw of the M600DF to be superior to that of the 600 lumen X300U and the area of illlumination about four times larger since the diameter of the hot spot is about twice the size. It's bright, and lights up a large area. You can see the shape of the M600DF beam in the photo below - it has a very bright spot with good peripheral spill. It's not a tight focused beam, and not a flood either, but described as a 'beam with reach and surround light'; which is usable at close and far applications. I'd say that it's an accurate description of the beam.

Excited to try out the M600DF in different configurations, I tried to install the UE tailcaps from my older M300 and M600 Scout lights, but they wouldn't fit. They'd only screw on part way. Weird, since the Z68 tailcaps were interchangeable. I contacted SF's tech rep and they said that some of the older ones may not fit, but it's been a while, and sent out a current UE tailcap. I've illustrated the differences below between the two for reference. The older UE tailcap has some features inside that prevent it from being screwed down all the way on the M600DF body. Since few of my rifles have quad Picatinny rails any more, I tried the M600DF with some of Arisaka Defense's excellent Scout-compatible mounts. Even with the slight increase in body diameter, the M600DF could be used in all of the configurations that worked with the M600 body.

I did catch wind of some early battery-related issues of the DF shutting off intermittently from the constant-on mode, and tried leaving the DF on for 10-15 mins without shutting it off, to see if I'd encounter the same issue. It stayed on, and it also gave me a chance to see how hot the head got. It did get hot, but not enough to burn (even though there's a Caution warning on the head). The switch to the SF18650B battery might have been the in-line fix in response to the earlier battery issues. SureFire does not recommend using 18650's of any other brands in the DF.

Overall, I'm very impressed with the M600DF and the versatility it offers with it's 'dual fuel' feature. It's still compact enough to be considered a 'Scout' light, and is a great balance of size, weight and output.

Beam shape

Older UE tailcap does not fit

Newer vs older UE tailcaps

Thumbscrew clamp removed

Arisaka mount installed with current UE tail

Mounted to VIS-KM with UE tailcap

Mounted to SCAR16