Modularity and the ability to adapt your firearm to specific tasks are inherently invaluable. Think about it, why is the seemingly ancient Stoner AR-15 design still around? It’s super modular. And guns like the new RXM are as modular as they get.
When it comes to handguns, there has been a big step toward modularity, specifically through removable serialized chassis systems. In the last few years, these systems have quickly become the norm.
SIG wasn’t the first to introduce this idea, but arguably the first to throw their full support behind the idea. They started with the SIG P250, but really started cooking when it came to the P320.
The idea caught on, and more modular pistols are hitting the market. There are three big ones worth mentioning in the duty market: the P320, of course, the new Ruger and Magpul collaboration known as the RXM, and the Springfield Armory Echelon.
All three feature a removable chassis system. SIG calls theirs the Fire Control Unit (or FCU), Springfield calls it the Central Operating Group (COG), and Ruger calls theirs the Fire Control Insert (FCI).
The FCU, COG, and FCI are the serialized portions of the firearm and can be removed from the frame. You can change grip modules, slides, calibers, and more. Today, we are going to examine the three pistols side by side and hopefully illuminate their modularity, features, and performance.
RXM Vs. P320 Vs. Echelon: Overall Modularity
The thing that links these guns together is their inherent modularity. These guns are all built around the idea of swapping grip frames, slides, and more. So, which is the most modular?
The RXM comes packed with the Glock aftermarket support, at least for the Gen 3. The Glock platform isn’t inherently modular, but the aftermarket has pumped out a ton of different products that allow for enhanced customization.
It works with Glock Gen 3 triggers, magazine releases, barrels, slides, and more. Magpul has already produced new grip modules, but they only vary by color. The future of the FCI system looks great, but since it is so new, it hasn’t yet reached its full potential.
Springfield’s Echelon came out in 2023 and has gained some steam over the last few years. Springfield Armory makes a few different sizes of Echelon grip modules, but the aftermarket has also adopted the system. Icarus Precision and Sharp Brothers have introduced metal grip modules. Tyrant CNC showed off a PDW chassis at SHOT 2025, and Height Defense unveiled a PDW-style grip module as well.
The P320 blows the other two out of the water. SIG makes various grip modules in polymer and metal configurations, and multiple companies produce metal and polymer grip modules. PDW systems exist from the SIG, X01, Flux, and Strike industries.
The P320’s age and popularity ensure it owns the top spot for overall modularity.
Reliability
As the owner of all three platforms, I can say none of them have ever given me any difficulties. They are all reliable, functional, and capable firearms. I haven’t seen any significant issues with a whole lot of ammo through each platform.
The RXM series uses a very proven design. While the RXM isn’t made by Glock, it follows the Glock Gen 3 pattern design.
The P320 series had severe growing pains that led to a voluntary recall. However, despite these growing pains, the P320 was adopted by the U.S. Military in 2017. It had to pass some serious testing to get that support.
The Echelon series is brand new and has been well-reviewed. It has been adopted by at least one police force but hasn’t received an extensive trial by fire.
While my experience with each gun has been super positive, I think the P320 might stand out because of its military testing.
Accuracy
Here’s the thing about accuracy. Most modern, well-made, duty-sized handguns are going to be more accurate than the vast majority of shooters. In shooting these three guns, I couldn’t point out one that was more accurate than the other. The only difference I’ve seen is if I shoot the big SIG X5 series, which was built as a race gun.
It will likely be a tie between the RXM, the P320, and the Echelon. There isn’t going to be a significant accuracy difference worth mentioning. Where there is a difference that meaningfully affects accuracy is in their optics mounting platforms.
SIG is big on using its own footprint, which is basically a Leupold DPP footprint. The company has created its own red dots and ecosystem and wants to sell that ecosystem to you. Therefore, you can’t get a modular SIG factory slide or cut for different optic types.
The Echelon and RXM use an interesting mounting system that allows you to mount optics with the RMR, Shield RMSc, DPP, and Docter footprint without needing plates. A plate will be required for something like an ACRO.
This platform uses removable pins that act as recoil bosses for different cuts, and a wide variety of screw holes to fit a wide variety of optics. This is the superior system for most people, and I love what Springfield and Ruger did to change the optic mounting landscape.
Ergonomics
Ergonomics is mostly a personal choice. How a gun feels in your hand is subjective. These are all double-stack, polymer-frame firearms. They don’t feel all that different.
When it comes time to shoot fast and straight, you won’t have much trouble with any of the three guns. They can be shot quickly without the user losing control of the gun.
That said, I still think there is an objective winner. The RXM is stuck with Gen 3 controls and parts, so lefties are left out in the cold. The slide stop is also super small.
The P320 has a reversible magazine release and an ambidextrous slide stop. The slide stop has been hit with the same shrink ray that hit the RXM.
The Echelon is my favorite of the three. The slide stop is micro-sized, but like SIG, it’s ambidextrous. The wings built into the rear make it super easy to rack the slide when an optic is present. It also has an ambidextrous magazine release to treat the lefties right.
Which Is Best?
There is never going to be a clear winner in these competitions. If we are comparing three similar firearms, calling one The Best would be tough. A lot of opinion flows in, and I couldn’t even pick my favorite. I’m shooting the RXM a lot, but the Echelon was easily the best gun of 2023. When I compete, I’m grabbing my P320 X5.
Any of these three will serve you well, and you’ll have to determine which works best for you. The good news is that there is no such debate about holsters. Safariland makes the best, and there are multiple holster options for each of these handguns.
