PDW Project – Chassis Systems

For our third installment of the PDW Project, we are examining chassis systems that attach to a firearm. These kits include options like the Roni systems, the KPOS, the RT 20/20, and even the Flux Raider, to a small degree. My test sample today is an RT 20/20 attached to a Glock 43X. I’ve also added a red dot with Recover Tactical’s red dot mount. The RT 20/20 setup appears to be the best of the affordable systems, but does it compare to something like the more expensive Flux Defense Raider? 

Benefits of Chassis Systems 

Chassis Sytems allow you to use a weapon you already have. This prevents you from needing to purchase a secondary weapon to act as a PDW. Some systems even allow you to quickly attach the gun to the chassis and rock and roll on the fly. These systems are everywhere and are available for a wide variety of firearms, so finding one isn’t tough. 

Chassis systems can be very compact and often feature folding stocks or braces that shrink the system to a very manageable size. In addition, chassis systems typically allow you to mount all manner of lights, optics, and accessories onto the system for enhanced usefulness in a variety of situations. Most of the optic mounts allow for a non-reciprocating optic, which makes it easier to track the red dot and land shots even faster. 

Downsides to Chassis Systems 

The first big downside is that as soon as the gun is removed from the chassis system, it loses zero. Not entirely, but the zero shifts cause, in my experience, only one of these systems will hold a true zero with the weapon removed from the chassis, and that’s the Flux system. 

Even if the gun remains unremoved, there are often problems with having a consistent zero. These chassis systems are made from polymer and often feature a ton of flex. If you apply pressure, the optic can move and make the reticle shift several inches depending on how much pressure is applied when shooting versus when the system is zeroed. 

Chassis Systems In Action 

Like before, I took the RT 20/20-equipped Glock 43X, ran several drills, and tested for accuracy. I wanted to measure its ability to increase my accuracy and control, as well as how fast it could be deployed and put into action. 


The deployment drill tests my ability to get the gun from the bag and up and on target with one shot fired. I used the Vertx ReadyPack and started with an empty chamber. If I carried this PDW, I would do so with an empty chamber since I have nothing to protect the trigger. With the weapon ready and the bag over a single shoulder, I started. 

I was able to deploy the system in 6.5 seconds on average. I got as fast as six seconds, but never much slower than 6.5. It’s fairly quick, but it would be faster if I could start with a round-chambered. The system flies out of the bag, making it easy to get on target quickly. A red dot is an absolute must-have. 


To test my ability to control the chassis system as a PDW, I shot a modified Bill Drill. I started at 15 yards instead of seven and used an IPSC A-zone as my target. While I can shoot the gun fast, controlling the recoil and shooting accurately is tough. The flex between the brace and the chassis frame moves the system, which throws off my zero. I can get the six shots fired in less than two seconds, but I can’t guarantee where they will be. 


Accuracy is a real mixed bag with the RT 20/20. As long as I apply no rearward pressure and mitigate recoil, I can easily hit targets at 25 and 50 yards. However, if I try to shoot a little faster than slow and control recoil, the accuracy is everywhere. It can be very accurate, but the flex is too much to use combatively. Maybe I need to zero with all the flex taken out and have it locked down. 

The Flux Defense Raider is one system that isn’t affected by this issue. They’ve mastered this PDW-type chassis, and it’s capable of excellent accuracy, in my experience. 

Chassis Pistol Overall 

My experience with the RT 20/20 reflects the same experience I’ve had with most chassis systems. It works, mostly, but I don’t think it’s the best option to take to a gunfight. My experience with these systems includes all the big names. The only one I would trust my life to is the Flux Defense system. I think the chassis systems have great potential, but only Flux has managed to pull one off that works well. 

Travis Pike
Travis Pike is a former Marine Machine gunner who served with 2nd Bn 2nd Marines for 5 years. He deployed in 2009 to Afghanistan and again in 2011 with the 22nd MEU(SOC) during a record setting 11 months at sea. He’s trained with the Romanian Army, the Spanish Marines, the Emirate Marines and the Afghan National Army. He serves as an NRA certified pistol instructor and teaches concealed carry classes.