SIG Sauer P365-FUSE COMP: Slide-Integrated Compensator Meets Enclosed Red Dot

Slide-Integrated Expansion Chamber

The defining feature of the FUSE COMP is its compensator built directly into the slide. Rather than threading a standalone comp onto the barrel, SIG machines an expansion chamber into the slide itself, venting gas through ports ahead of the muzzle to counteract muzzle rise. Paired with a 3.7-inch carbon steel barrel, the system delivers flatter shooting without extending the pistol's footprint. Overall length stays at 7.2 inches, identical to many uncompensated P365 variants.

This approach mirrors what SIG did with the original P365-FUSE, but the COMP variant shortens the barrel from 4.3 inches to 3.7 inches while adding the expansion chamber. The result is a pistol tuned specifically for recoil management in a carry-sized package. Aggressive FUSE-pattern slide serrations provide positive purchase for press checks and malfunction clearing, even with wet or gloved hands.

ROMEO-X SIG-LOC Compact Enclosed Optic

The FUSE COMP ships with the ROMEO-X SIG-LOC Compact, a fully enclosed, sealed, and gas-purged red dot with a circle dot reticle. The optic mounts from underneath the slide using SIG's proprietary SIG-LOC system, which SIG claims delivers the strongest optic lockup in the industry. The under-slide mounting produces a low deck height that allows standard-height co-witness with the included X-RAY3 day/night iron sights.

The enclosed emitter design shields the LED from debris, lint, and carbon fouling that can obstruct open-emitter micro red dots during carry. The side-mounted battery means you can swap cells without removing the optic or re-zeroing. For shooters coming from the pistol red dot world of aftermarket cuts and adapter plates, the factory SIG-LOC integration eliminates the compatibility guesswork entirely.

Full Specifications

The Mainline Version of the DH3

The FUSE COMP is effectively the production version of the P365-XF DH3 Daniel Horner signature series that SIG introduced at SHOT Show 2026. The core specifications are nearly identical: the same 3.7-inch barrel, the same slide-integrated expansion chamber, the same SIG-LOC compact optic footprint, and the same flat-faced trigger. Where the DH3 differentiated itself with Coyote Cerakote, custom lightening cuts, and Daniel Horner branding, the FUSE COMP wraps the same compensated platform in SIG's standard Nitron finish with FUSE-pattern serrations and ships it as a standard production SKU.

The key upgrade over the DH3 is the included optic. The DH3 ships optic-ready but without an optic; the FUSE COMP ships with the ROMEO-X SIG-LOC Compact already factory-mounted. That's a meaningful difference, since the enclosed ROMEO-X Compact with circle dot reticle runs $200-300 separately, and the factory SIG-LOC mounting ensures zero-tolerance fitment from the box. The DH3 also offers a premium AXG alloy grip variant that the FUSE COMP does not.

Compared to the original P365-FUSE (4.3" barrel, standard ROMEO-X, fiber optic sights), the COMP variant trades barrel length for the expansion chamber and upgrades to the enclosed SIG-LOC Compact optic with day/night backup sights. For existing P365 owners looking to upgrade rather than buy a complete pistol, our P365 upgrades guide covers aftermarket slides, triggers, and optic options.

Carry Considerations

At 25.4 ounces unloaded and 7.2 inches overall, the FUSE COMP is heavier and longer than the base P365 (17.8 oz, 5.8") but comparable to the P365XL. The M1913 accessory rail accepts compact pistol lights like the Streamlight TLR-7 Sub or SureFire XSC, adding capability for a dedicated nightstand or carry setup. The interchangeable backstraps (small, medium, large) accommodate different hand sizes without requiring aftermarket grip modules.

The lack of a manual safety option is worth noting for shooters whose carry method or comfort level requires one. SIG is explicit that this model will not be offered with a manual safety. The flat-faced trigger and X-RAY3 day/night sights are standard for the current P365 generation. Holster compatibility will depend on the FUSE COMP's specific slide profile; expect the major holster manufacturers to release fits shortly after launch.