FRIDAY NIGHT LIGHTS: PK Designlab’s M51-WIR White/IR Weapon Light Review

    For those of you who are hardcore flashlight aficionados, the name PK is well known. For those who don’t know PK (Paul Kim), he designed most of your favorite SureFire flashlights. The Scoutlight, Hellfighter, X300 and loads more were his designs. He left SureFire to start his own company and he calls it PK Designlab. He came out with a couple of handheld lights and a couple years ago he came out with the Rocket, a single cell weapon light. Last April he teased the flashlight world with his designs for a new line of weapon lights. Well, now he is coming out with his white/IR weapon light called M51-WIR. He also has a new tape switch that is SureFire compatible and features a 90° plug.

    Photo Credit: PK Designlab

    Photon King IR Weapon Light

    In the world of IR weapon lights, the SureFire Vampire is the reigning king. Those who shoot in the dark know that laser IR illuminators are really the way to go but if you want an IR LED weapon light the only choice is the SureFire Vampire. Well, that is about to change. The Vampire was designed by PK back when he was at SureFire.

    PK’s first foray into his own weapon light was the PK Rocket. It is a single cell all white weapon light with a built-in Picatinny mount. Below you can see the Rocket next to the new M51-WIR. The body styling has been toned down a bit from the Rocket and the corners of the mount have been rounded off to eliminate snagging.

    One minor issue I had with the Rocket was the aggressive defender style tail cap. If you are familiar with the SureFire defender series of lights, they have crenelations around the bezel and in some cases like the E2D-Defender, there are crenelations on the tail cap. This is so you can use said Defender lights as a striking implement for self-defense. This makes sense for a handheld light but not so much for a weapon mounted light. Especially since the pointy end is pointed back at the shooter. Trying to push the tail cap for momentary activation gets a little dicey while trying to do that with a gun that recoils. Just imagine those somewhat pointed bits jabbing rearward into your thumb. Not a great design for a weapon light.

    Well, there is good news. PK changed the design on the M51-WIR and shrouded it just like the Scoutlight tail caps. Also, these tail caps are backwards compatible with the Rocket.

    Due to the patent surrounding the SureFire Vampire, PK went with an offset IR LED.

    M51 WIR and Rocket bezel

    M51-WIR on the left, Rocket on the right

    The M51-WIR is sort of like a Scoutlight M300V. You pull the collar on the head forward and rotate it to switch between white and IR. What sets it apart from the Scoutlight M300V is the amount of light it produces. The M600V Scoutlights produce at best 320 lumens of white light and 120 mW of IR light. The M51 and the Rocket pump out 550 lumens of white light. And the M51-WIR in IR mode cranks out a staggering 540 mW. Just so you know, I am comparing apples to oranges a little bit here. The M600V is a 2xCR123 6V weapon light while the M51-WIR runs on a single CR123. It runs on a single battery and outperforms the M600V.

    There is a slight drawback to pushing that many lumens and that is battery life. The M300V from Surefire lasts 1.5 hours but the M51-WIR has a run time of just one hour. But if you think about 250 lumens for 1.5 hours vs 550 lumens for just 1 hour, yes you lose a 1/3 of the run time but you gain 220% in lumen output and that is just white light. The M300V only has 100 mW of IR light compared to the M51’s 540 mW. Now if you go back to the M600V it has a longer run time of 2.5 hours which is nice but you can get 2 hours with the M51-WIR, you just need to change batteries.

    Here is the V1 Vampire head on an M300 Scoutlight body in comparison to the M51-WIR.

    What Does The Beam Look Like?

    When you get down to it, all that really matters is how well does it perform downrange?

    This is a control with no lights using the SiOnyx Aurora set to night mode.

    First up is the SureFire V1 Vampire white light. It has just 250 lumens and a tighter hot spot for more throw down range.

    SureFire V1 Vampire

    Here is the same shot but using the 550 lumens of the M51-WIR. The M51 has a wider beam and less of a hot spot.

    PK Designlab M51 WIR

    The white beam patterns are more noticeable when I shine it on this sound wall.

    V1 Vampire white light beam pattern.

    The M51 was developed as a CQB light and while the V1 has a brighter-looking hot spot, you have better situational lighting with the M51.

    M51 white light beam pattern.

    Since the IR LED in the M51 is offset you do get some artifacts in the beam pattern whereas the Vampires have a centralized IR LED for a smoother and consistent beam pattern.

    V1 Vampire on IR mode


    M51 in IR mode

    Under night vision, my PVS-14, the difference is not as noticeable at close distances.

    V1 Vampire in IR mode

    M51 in IR mode


    Earlier I was at the same spot and brought out a rubber dummy target and I set it out at 100 yards.


    Later my friend Josh and I went to a local shooting spot to really test the M51 at distance in an area with no ambient light, no moon and cloudless sky. Here you can see the difference.

    The M51 IR light was able to reach out much further than I expected and in this test with these variables in lighting the dark spots of the M51 were not as bad as I had previously thought.

    PK’s New 90° Tape Switch

    Going back to the Rocket weapon light, it only has a tail cap that has a clicky button. So PK has made a new tail cap adapter for the M51 that comes with a tape switch tail cap and it is SureFire compatible. Something that SureFire weapon light tape switches have been needing is a 90° plug.  Well, PK is making one. It seems like such an innocuous feature to have a simple 90° bend in the plug but take a look at your Insight ATPIAL plugs. They are all 90° plugs. It keeps the wires tucked in closer to the gun and is less likely to get snagged and unplugged.

    PK on left. SureFire on right


    Here is the M51 with the tape switch and new tailcap and adapter.

    The 90° plug allows for better wire management.

    The pressure pad has the same dimensions as a SureFire tape switch so you can use a Cloud Defensive Light Control System or any other device to hold the PK tape switch in place.

    The adapter is SureFire compatible with SureFire Scoutlight tail caps. Below I have mounted a tan Scoutlight rear cap with SR07 tape switch.

    Here is the M51 with tail cap adapter and Scoutlight tail cap. 

    There is room for improvement. The head of the M51 is a little too smooth for my liking. While there is a ring of knurling, It is not aggressive enough. I would prefer a change in the landscape. Some deeper grooves or raised ridges. You could have the bezel flare out a bit so when you pull the head forward to unlock the collar, your fingers don’t slide off as easily. I would also change the mount design. Picatinny mounts are obsolete. Use a Scoutlight pattern or some design that is compatible with Scoutlight mounts. This allows for the most streamlined and modular method of attaching the M51 to your weapon of choice.

    The PK M51-WIR will be available on their website with an MSRP of $299. They are still working on pricing as I type this. They will be offering the tape switch, tail cap adapters with tail caps for those who want to upgrade their Rockets or M51-WIR weapon lights. I have been told they will sell the tape switches separately for those who want to upgrade their Scoutlights as well.

    Nicholas C

    Steadicam Gun Operator
    Night Vision & Thermal Aficionado
    Flashlight/Laser Enthusiast
    USPSA competitor

    Any questions please email him at [email protected]