Tech Tip: Tyrant CNC Sig P365 Chassis
In this build, Caleb installs the Tyrant CNC TWS 365 modular pistol chassis on a SIG P365. The goal is to create a compact, rigid platform that adds stability, accessory mounting capability, and onboard spare magazine storage while retaining the core reliability of the P365 fire control unit.
WHAT THE TWS 365 CHASSIS IS
The TWS 365 is a modular aluminum chassis designed around the SIG P365 FCU. Instead of housing the FCU in a traditional polymer grip module, the TWS 365 uses a rigid aluminum core with polymer grip panels. This keeps weight down while providing a solid, consistent interface for the shooter.
One of the standout features is onboard magazine storage. The chassis carries the active magazine in the pistol and a spare magazine up front, giving you two magazines on the gun without adding external pouches.
UNBOXING AND COMPONENT OVERVIEW
Out of the box, the TWS 365 includes the main chassis, an optional front shield, mounting screws with an extra included, and a folding, spring-loaded brace assembly. The chassis features a full-length bottom rail, allowing direct mounting of a weapon light even if the front shield is removed.
Caleb’s host pistol already includes a Radian Ramjet, and the TWS 365 design allows that setup to remain intact, showing compatibility with popular compensator-equipped P365 builds.
SAFETY CHECK AND DISASSEMBLY
As always, the install starts with a safety check. The magazine is removed, and the pistol is field stripped. The slide is set aside so attention can be focused on removing the fire control unit from the original grip module.
REMOVING THE SIG P365 FCU
The FCU is retained by a rear pin that includes a retainer clip. Caleb explains that pushing the pin from right to left makes removal easier because of how the retainer is positioned. Once the pin is removed, the FCU lifts up at the rear and pulls free from the frame.
Care is taken to keep the retainer clip in place so it does not get lost during the process.
INSTALLING THE FCU INTO THE TWS 365
The FCU installs nose-first into the TWS 365 chassis. The fit is intentionally snug, tighter than a standard polymer grip module. This tighter fit helps improve consistency and rigidity.
Once aligned, the FCU pin is reinstalled. Because of the tight tolerances, a punch is used for leverage to seat the pin fully until it snaps into the retainer.
REINSTALLING THE SLIDE AND TAKEDOWN LEVER
With the FCU secured, the slide is reinstalled. Caleb points out that if the takedown lever refuses to rotate down, lifting the slide catch will allow it to move freely. Once aligned, the slide locks in place normally.
FRONT SHIELD INSTALLATION
The chassis can be used with or without the front shield. In this build, the shield is installed to protect the support hand when using a compensator and shorter barrel setup. The shield slides onto the rail section and is secured with two screws.
Thread locker is applied, and the screws are tightened to 8 inch-pounds. The extra screw included in the kit is simply a spare.
FOLDING BRACE INSTALLATION
Next, the folding brace is installed. Caleb removes the brace screws, applies thread locker, and tightens them down. The brace folds for compact storage and deploys quickly using a spring-loaded mechanism.
Deployment can be done with the support hand or firing hand, depending on hand size and personal preference.
WEAPON LIGHT MOUNTING AND ERGONOMICS
With the rail exposed, a weapon light is mounted directly to the chassis. Caleb positions the light forward and tightens it securely. Even with the light installed, there is adequate grip space, especially when the spare magazine is in place up front.
Caleb demonstrates how the spare magazine integrates into reloads. When the primary magazine runs dry, the spare is removed from the chassis and inserted, allowing the shooter to stay in the fight without reaching for external gear.
SLING OPTIONS AND QD POINTS
The TWS 365 includes QD sling mounting points and a single-point sling attachment option. These features allow flexible carry and staging configurations depending on how the system is intended to be used.
COMPENSATOR AND SUPPRESSOR CLEARANCE
The top of the chassis is open, allowing compatibility with compensators. Suppressor clearance depends on diameter. If a suppressor is too large to fit under the shroud, the shroud can be removed while still retaining the weapon light on the chassis rail.
FINAL THOUGHTS
The Tyrant CNC TWS 365 is a well-designed modular chassis that adds meaningful capability to the SIG P365. With a tight FCU fit, folding brace, onboard spare magazine storage, and full-length rail, it offers a compact and controllable setup without a complicated installation process.
This build shows exactly how the TWS 365 installs, how it interfaces with common P365 upgrades, and what kind of functionality it brings once assembled.
