SIG Sauer released the P365 in 2018 to much fanfare, largely because of its industry-leading size-to-capacity ratio. Before the P365, most of us were stuck with single-stack 9mm pistols that could at most hold 8 rounds with a magazine extension—my Smith & Wesson Shield being a prime example of this. Today, specifically because of the P365, we have much better options from almost every handgun manufacturer, but no other manufacturer to date has done what the SIG Sauer P365 can do—swap frames, slides, controls, and triggers all without having to buy a new firearm. I’m of course talking about the SIG Sauer P365 Fire Control Unit or FCU. The FCU on a P365, and on its bigger brother the P320, is considered the registered part of the firearm. The FCU, made out of tough steel, is the core of the firearm and can be configured with any and all of SIG Sauer’s P365 slides, grips, trigger shoes, and controls.

 

Having a highly customizable pistol was once firmly in the realm of fantasy or video games. The FCU makes customizing your handgun to your preferences a lot easier by giving you the ability to swap large and important features like your slide length or grip size on the fly without the need to go buy an entirely different handgun. When it comes to what Tyrant Designs does best, if you swap out all your basic concealed carry features for more enhanced controls, you won't need to abandon these controls should you later decide to use a Tyrant Designs P365 compensator and magazine extensions in an IDPA or USPSA match.

 

sig sauer p365 fire control unit fcu

 

Beyond just accessories, the P365 gives you the ability to keep the same trigger—perhaps one of the Tryant Designs Intellifire triggers—while modifying your grip and slide length for better concealability in the summer, or for better performance with gloves during the winter. When it comes to what I do, having the ability to swap a single self-contained piece with other critical firearm components is important for reviewing a lot of the different configurations of the P365, as well as the accessories that companies like Tyrant Designs offer. Simply put, the beauty of the SIG Sauer P365 Fire Control Unit lies in its modularity. This modularity ultimately puts the entire design of the firearm in the hands of the end user, meaning you can customize the gun exactly how you want it, and ensure that any aftermarket accessories you want to include in your new dream EDC gun can be accommodated.

 

The FCU is just one of the reasons I love and still carry my original SIG P365 around. These days the little 9mm micro compact is heavily modified but the same FCU that I purchased back in 2019 is still being used, carried, and shot today and that’s not something I can say about most of my other carry guns. Let us know why you like (or don’t like) the SIG Sauer P365! Have you ever tried to tinker with your P365 by swapping out slide assemblies or grip modules? Let us know what your FCU has turned into, we’d love to see it!