Sig Sauer P320 9mm Custom Works FCU Build – Legion Gray Full-Size, Optics-Cut Slide, 5.5 in 1/2x28 Threaded Barrel, 21+1
This full-size Sig Sauer P320 was assembled from a Custom Works Fire Control Unit and configured with a gray Legion-pattern polymer grip module and flared magwell. It features a gray SIG-marked, optics-cut slide with lightening windows, a 5.5 in 1/2x28 threaded barrel, and a flat, skeletonized gold trigger. Chambered in 9mm Luger with a 21+1 capacity, it delivers a distinctive, Custom Works FCU-based setup with practical performance touches throughout.
Condition
Overall Condition: Good condition, showing some signs of prior use and handling.
Bore Overall Condition: Good - Clean, well-maintained, minor wear marks.
Bore Rifling: Good Rifling - Intact, well-defined lands and grooves.
Specific Condition Notes: This firearm is in solid shape. It shows various cosmetic imperfections, including scratches, blemishes, and areas of finish loss.
What's Included
- SIG Sauer Legion soft pistol case (gray)
- SIG Sauer P320 Custom Works FCU box (SKU 8900160; label present)
- P320 Custom Works Fire Control Unit insert/brochure
- One 21-round magazine
Built off a Sig Sauer P320 Custom Works FCU, this pistol anchors the configuration with the factory flat gold trigger and FCU labeling dated 03-MAR-2021. The frame is marked NEWINGTON, NH, USA, and the setup retains the striker-fired system and full-size format favored for controllability and sight radius.
The grip module is the Legion-pattern polymer unit in gray, sized full-length and fitted with a flared magwell. This module pairs a sure hold with fast magazine seating while keeping weight down, and it complements the pistol’s gray slide for a cohesive look.
The SIG-marked slide is finished in gray and includes forward and rear serrations, lightening windows, and an optics cut. The serrations and windows provide confident purchase and a distinctive profile, while the optics cut adds mounting flexibility consistent with modern P320 configurations.
A 5.5 in threaded barrel with a 1/2x28 thread pattern extends capability at the muzzle. Sights are dovetailed iron units with a green-dot front and square-notch rear. An integral Picatinny accessory rail is machined into the dustcover. The included steel double-stack magazine is numbered with witness holes to 21.