Last updated on February 22nd, 2026 at 02:27 am

Sig P320 X5 Legion…Flush Comp Review

(Scroll Down for Full Setup & Specs List)

The SIG Sauer P320 X5 Legion is already a phenomenal competition pistol right out of the box. But what if we could make it even better? What if we could setup a version that’s customized from the ground up to be an incredibly flat-shooting, high-performance machine? That was exactly the goal of my latest project: setuping a P320 Flush Comp X5 Legion from an Partial module, complete with a custom slide and a semi-flush compensator.

After putting it all together, the first few shots confirmed it: compared to a regular P320, this custom setup is way flatter. Let’s dive into how it all came together.

My Favorite 9mm Pistol Cleaning Kit

Use Code TTB10 for 10% OFF + FREE SHIPPING on Orders $150+

Best Lube I’ve Tested

My Favorite Wireless Electronic Hearing Protection

Pricey, But Worth It

My Favorite EDC Gun Belt – Designed for Appendix Carry

P320 X5 Legion Here

Use Code TTB10 for 10% OFF Orders $150+ w/First Link w/Brownells Links

The Parts: A Recipe for a High-Performance Pistol

This isn’t your standard setup. The goal was to create a pistol that could outperform the original X5 Legion, particularly in recoil management. To do that, I hand-picked a selection of high-quality components.

Here’s a look at the key parts used in this setup:

• Partial Module (MUP-1): The foundation of the setup is an Partial Fire Control Unit (FCU) insert. This is the serialized part of a P320, and finishing it yourself is a rewarding project. The process involves using a jig to drill a few holes and bend the slide rails into place. While it requires a drill press and some patience, it’s what makes this a true custom setup.

• SIG X5 Legion Grip Module: This isn’t just any polymer frame. The Legion grip is infused with tungsten, making it significantly heavier than a standard grip. This added weight is crucial for absorbing recoil and keeping the pistol stable during rapid fire. It also comes with a flared magwell for faster reloads.

• Norsso Compact Slide: I opted for a custom Norsso slide, which is not only aesthetically pleasing with its aggressive serrations and window cuts but is also machined to tight tolerances for enhanced performance.

• Parker Mountain Machine Barrel & Compensator: This is the secret sauce for making the gun shoot so flat. The Parker Mountain Machine (PMM) setup uses a proprietary shortened barrel (made by Faxon Firearms) paired with a dual-port compensator. This combination is designed to perfectly fit the slide, giving it a nearly flush look while significantly reducing muzzle flip.

• Upgraded Trigger System: For the trigger, I combined the excellent flat-faced SIG X5 trigger shoe with an Apex Tactical enhanced trigger bar and a lightened spring kit from Tactical Pontoon. The result is a crisp, clean break with a pull weight of just over 3 pounds—perfect for competition.

• DPM Recoil Reduction System: To further tame the recoil, I installed a DPM guide rod and spring kit, which uses multiple springs to create a smoother recoil impulse.

Parker Mountain Comp

The Setup Process & Final Thoughts

Assembling the parts onto the completed Partial module was straightforward. The modularity of the P320 platform makes it feel like setuping with Legos for adults. Once assembled, the pistol felt incredible in hand. The weight of the tungsten-infused grip gives it a solid, balanced feel that immediately inspires confidence.

The final product is a unique, high-performance pistol that looks as good as it shoots. The combination of the heavy frame, the compensator, and the recoil reduction system is designed to create an incredibly soft and flat shooting experience, allowing for faster follow-up shots on target.

The next step is to hit the range and put this setup to the test against a factory X5 Legion. Will it live up to the goal of being a flatter, faster competition gun? Stay tuned to find out

X5 Optic RMR Adapter Plates