TFB Review: FLUX Raider MP17 – P320 PDW Chassis

    FLUX Defense made a name for themselves with their brace for Glock pistols. Since then they came out with their MP17 aka FLUX Raider. It is the most anticipated P320 chassis and even though they have been making it for a while, the demand has not died down. They sell out in minutes. I managed to get one thanks to my friend Alex K. of Nocorium. He had a spare and sold it to me at his cost. So let’s see what makes the FLUX Raider so great.

    SIG P320 @TFB:

    Flux Raider in Tesla

    For those of you not familiar with how P320 chassis work, it is all about the genius behind the P320 design. Typical handguns use the frame as the serialized firearm. SIG changed this recipe and registers the Fire Control Unit (FCU) aka trigger module instead of the frame. Since the FCU is the serialized component you can change the frame and even the caliber. While SIG Sauer only offers you the ability to go from full size down to subcompact, it has been third party companies like FLUX Defense to think outside the box and rehouse the FCU into a chassis to give your P320 more features. And the FLUX Raider is packed full of them.

    As mentioned earlier, FLUX Defense started off by making a brace for Glock pistols.

    While it works, I found it to be a bit unpleasant to shoot. I had difficulty getting a comfortable sight picture. I would have to bury the brace bars deep into my cheek to see through the RMR mounted on my Loki Tactical milled 19X slide.

    That is not the case with the MP17. I got to test fire one at SHOT Show 2020. Here are some pics I took at SHOT Show Range Day. You can see some major design changes from this versus the current form of the Raider.

    FLUX MP17 holster. According to FLUX Defense, there are only 200 of these made.

    The FLUX Raider has gone through some significant changes since it was announced almost two years ago.

    Close Up FLUX Raider

    The FLUX Raider chassis comes in a simple cardboard box with a skull and crossbones printed on the lid. The chassis is pretty straightforward. It is just like your standard P320 frame or other chassis. Here is the Raider next to a B&T P320 chassis and the FCU X01 chassis.

    Installation is rather simple for P320 owners. Just remove your slide, takedown lever and FCU. Then reinstall them into the Raider chassis. Fully built it is not as compact as you think. It is almost as big as my SP5K-PDW.

    One of the changes from the pre-production MP17 is the optic rail. Before they had a flat top metal optic plate to bolt RMR style optics. They have since changed that design to a Picatinny rail that is molded.

    This opens many options for optics. I went with the Holosun HE509T because I wanted an enclosed emitter.

    The optic mount has a tunnel that allows you to aim with the iron sights on your slide if you so choose.

    One problem with this tunnel is when you suppress the P320. When you shoot a typical semi-automatic handgun suppressed, the pistol is in your hands and your arms are almost at full extension. This positions the pistol far from your face. This is not the case with the FLUX Raider and Glock brace. Now the pistol is right up in front of your face. With regards to the Raider, the tunnel channels suppressor blowback into your face. However, if you are aiming with a red dot, your eyes and eye pro are slightly above this tunnel. So now the gasses shoot down the tunnel and hit your face and upwards behind your eye pro. My friend Arya, who made the NAIL adjustment lever for the DIY adjustable night vision aperture, made a plug that blocks the tunnel. You lose the ability to aim with irons but now you won’t be a victim of suppressor bukake.

    It is a sandwich that is bolted together to block the rear orifice. It is called “The Butt Plug”.

    Due to the reciprocating slide and position of the ejection port, you cannot have an optic more forward otherwise it can interfere with brass ejection.

    As you can see, I used my M17 and there are some things to consider when using the FLUX Raider chassis. I had to remove my slide-mounted Delta Point Pro as well as the frame safeties to fit into the Raider. Below is what my M17 looked like before I installed it into the MP17 chassis.

    The MP17 chassis does have witness marks for cutting slots to accommodate frame safeties but it is advised to not cut the chassis.

    Instead, you can remove the factory safeties and replace the safety with a factory bar from SIG. I got mine from AB Prototype.

    Photo by AB Prototype

    Before my safety delete bar arrived, I had to use my friend Kevin’s FCU to test out the Raider.

    Besides the auto-deploying brace, the coolest change to the MP17 chassis is the magazine release system. Yes, it is a system. In the pre-production version I shot at SHOT Show Range Day, the MP17 uses a P320 mag release and the spare magazine is held in place with friction. They have since moved away from this obsolete magazine retention method.

    Both magazines are held with their individual magazine catches. To release the main magazine in the pistol grip, there is a sliding bar that you push forward with your right-hand thumb.

    Or you can use the redundant magazine release on the right side of the chassis. Push it with your trigger finger and it pushes the sliding mag catch for you releasing the primary magazine.

    Why have a secondary mag release? I think it has to do with the ambidextrous safety. The MP17 has an integrated safety that blocks the trigger when activated. Flip it down to fire. One minor issue is that the safety lever sits really close to the left side mag release making it harder to access the mag release.

    What about the secondary magazine stores in the “NOT AN VFG”? There is a paddle-like magazine release.

    Now you use your non-dominant thumb to press this mag release forward. This magazine release has two functions. If you half-press the release, it drops the front magazine. Press the release all the way in and it pulls the rear magazine release as well. So both magazines are released at the same time. This way you can reload much quicker y pressing a single button.

    By changing to a one-piece molded chassis, they simplified the design and made the slide release bar also have a dual function.

    Pressing the lever down releases the brace but it also presses the slide release.

    Your P320 goes to slide lock. You reload using the FLUX mag release system, then all you have to do is use your trigger finger to reach up and press the brace release lever down.

    One might be concerned since this can also release the brace however when you reload the Raider there should not be any pressure on the brace and the brace has soft locking detents to hold the brace in the fully opened position. As long as you do not push the brace forward while you close the slide with the lever bar, you will be fine.

    The brace hides a hidden compartment. The 3D printed compartment holds a spare CR2032 battery.

    Since the MP17 Raider does not have accessory side rails, the only place to mount any lights or lasers is on the bottom rail.


    Streamlight TLR-VIRII

    Steiner DBAL-PL

    SureFire XVL2


    Aiming The MP17

    Due to the design of the MP17, your optic sits rather close to your face.  This makes it difficult if you like to aim passively with night vision.

    Typical night vision goggles stick out about 4 inches from your face. So getting behind your optic on a Raider is difficult. You can pull your head back and try to get your NODs behind the optic but it is awkward.

    If you have articulating binos, you can roll one pod up and aim passively with your unaided eye while your other eye is looking through night vision and your brain will merge the two images.

    There is a rather unconventional solution and that is to use a Steiner PVS-21. The Low Profile Night Vision Goggle (LPNVG) is extremely low profile. So it is easy to get behind your optic of choice.

    Cerakoting The MP17

    Thanks to James Gascon, he uploaded a video detailing how to disassemble and reassemble the FLUX Raider for Cerakoting. You can see it here.

    I stripped mine down and had my friend Ted of Darksoul Design Cerakote it in Magpul FDE but I had him coat the controls in dark bronze to give some contrast.

    FLUX Raider Wrap Up

    The FLUX Raider is insanely popular. They are made in small batches and sell out in minutes. You have some people price gouging trying to sell a Raider chassis for over $1000. Retail on the MP17 chassis is just under $500. It certainly has a lot of cool features. The magazine release system is particularly clever. Some parts of the chassis are still 3D printed like the 2032 battery storage and Raider plate. Even the secondary magazine button is 3D printed. I don’t have an issue with this. I suppose it simplifies their manufacturing and afford the mold for the main chassis. The Raider costs $459.99 if you are lucky enough to buy one at retail price.

    I am torn. I like the universality of the optic mount but I wish it was modular like the pre-production M17. I would like it if you could remove the hood entirely and shoot the Raider with a slide-mounted optic. Unfortunately, the only way to do that is to talk to FLUX Defense and they can instruct you where you can cut the hood off. Making it a permanent modification. I would not want to cut off the hood just to find out I don’t like it.

    There are some companies making accessories strictly for the MP17 Raider. makes a charging handle that bolts onto the P320 slide like the M17. They also make side rails that bolt to the sides of the chassis just above the bottom rail. Check them out on their website.

    I do like the Raider but have seen and heard people have issues suppressing them. Especially when you use a full-length slide. People end up getting aftermarket springs to get the slide to cycle properly. I have not tried with mine since I do not have a threaded barrel for my M17 but my friend Chris P. suppressed his and he said he had to get 1911 springs for his P320.

    If you want more added functionality for your P320, the FLUX Raider has it but good luck getting one. There is a Facebook group where Ben Griffith of Flux Defense is quite responsive and posts updates all the time. So if you want to get one, I recommend joining the group.

    Nicholas C

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

    Any questions please email him at [email protected]