The world of micro-compact semi-auto pistols never ceases to impress. A few years ago, I reviewed the original SIG Sauer P365 — a pistol that truly set the standard for the micro-compact category. Micro-compacts are often handguns with a locked-breach action that fire a full-power cartridge fit into the smallest possible space while keeping the highest magazine capacity possible. SIG’s innovative P365 design featured a 3.1-inch barrel and a 12-round magazine, all in a slim frame just 1.1 inches wide. The P365 not only delivered the power and capacity of a larger handgun but did so in a size perfect for concealed carry, outperforming competitors like the Glock 26.

Since the P365’s groundbreaking debut, SIG Sauer handguns have continued to innovate rather than rest on its laurels. While the original 9mm format pushed the boundaries of compactness, SIG Sauer has explored new ways to enhance and expand the P365 line. This brings us to the latest variant, the SIG P365 Fuse, designed to bridge the gap between micro-compact efficiency and the versatility of full-sized and mid-sized pistols. The P365 Fuse introduces exciting new features, including a red dot mount option, which makes it an attractive choice for those looking for a 9mm pistol with enhanced accuracy and performance.

Let’s dive deeper into the details of the SIG P365 Fuse and see how it builds on the legacy of the P365.

About the P365 Fuse

SIG designed the P365 Fuse as a “fusion of capability and concealment.” The Fuse’s design allows the user full-sized pistol capability with a 17-round flush-fit and two 21-round extended magazines included. Smaller than a traditional full-sized handgun even with the extended magazines, the P365 Fuse is easily concealable at a size and weight intended for comfortable all-day carry.

SIG Sauer P365 Fuse Specifications

Caliber: 9mm Luger
Magazine: Steel magazines with polymer baseplates; one 17-round include, two 21-round included
Barrel: 3.1 inches/carbon steel/non-threaded
Weight: 24.8 ounces
Overall length: 7.2 inches
Overall width: 1.1 inches
Grip module: Polymer/Laser-stippled X-Grip (LXG)/Flared magazine well/M1913 rail
Slide: Stainless steel/Nitron finish/front and rear grasping grooves
Electro-optic installed: SIG Romeo X Red Dot
Standard sights: Green fiber optic front/Black serrated rear
Trigger: Striker-fired action/Nickel-plated, flat-face trigger/Pull weight of 4 pounds, 4 ounces
Slide release: Extended
Manual safety: None
Weapon light: 700-lumen SIG Foxtrot 2R LED light Installed
Magazine release: Left side

With the addition of a 700-lumen SIG Foxtrot 2R weapon light already mounted and ready to go out of the box, my tested variant of the Fuse is set up for both concealed carry and home defense. It can also be removed by just a single screw. With ambidextrous paddle switches, either index finger can operate the momentary operations by pushing down or lock the light on by pushing up.

This Fuse variant also includes the Romeo-X red-dot optical sight. It features MOTAC motion activated illumination, which is extremely handy when reaching for your gun in the middle of the night. However, I would like to see Tritium sights rather than the plain black serrated rear sight and the fiber optic front sight. Under total darkness or from a ground position, the glowing green front and rear sights would help draw your eyes into alignment with the Romeo-X’s glowing red dot

Unfortunately, I was not able to test carry the Fuse with the light attached. Though my DeSantis M71 G2 inside-the-waistband holster accommodates a variety of handguns, the Fuse with the Foxtrot R2 attached did not fit. Finding a holster to fit the P365 Fuse may take more of an effort, or you can dismount the light for concealed carry.

Testing the P365 Fuse at the Range

I fired the P365 Fuse with my neighbor, a former Special Forces operator, using SIG Sauer 9mm 124-grain V-Crown Elite self-defense ammunition and 124-grain Elite Ball FMJ ammunition. Both loads exit the muzzle at approximately 1,165 feet per second and generate a pretty substantial 374 foot-pounds of energy; that’s 100 FPE more than the department issue .38 Special duty load used by my former law enforcement agency.

We fired from 21 feet, standing, with a two-hand grip. As expected, there was no difference in accuracy or feel of either SIG Sauer load. Both functioned perfectly through the Fuse. Recoil was managed easily enough, in part due to the additional weight at the muzzle provided by the Foxtrot R2 light. Control is also enhanced by the flared magazine well, which improves the overall grip.

While the 21-round magazines extend beyond the magazine well by 1 ¼ inches, SIG adds a u-shaped polymer cover that wraps around the exposed front of the metal magazine to provide a better grip. The rear of the magazine is open so the round count can be viewed in part. With 21-round magazines on board, one could certainly put up a spirited defense indoors or out.

Two replacement backstraps are also included with the Fuse, ensuring a more precise fit for the individual user, though I didn’t need to change the backstrap.

I don’t prefer flat trigger faces, but the one on the P365 Fuse was decent, with about ¼-inch of slack to take up before the actual pull begins. The undercut trigger guard enhances the grip feel. The slide release was easily reached for reloading and lock back. Disassembly comes via the takedown lever on the left side of the frame. Cycling was very smooth, and there were no failures to function.

My neighbor’s best group with the P365 Fuse measured a respectable 5 ½ inches across for 15 shots. My best group measured 4 inches with a called flyer that brought it to 5 inches.

SIG P365 Fuse: A Compact Powerhouse with Full-Size Features

The SIG Sauer P365 Fuse with Romeo-X Red Dot/Foxtrot 2R Tactical Light shows the versatility of the P365 design. It has just about everything a serious defensive user could want in a still compact package. The Romeo-X sight eliminates my main concern about previous generations of red dot sights: a manual off/on switch. There is no need to shake the Fuse to turn on the MOTAC. Simply pick it up.

The SIG Sauer P365 Fuse is a compact pistol with full-sized features. I found the SIG Sauer P365 Fuse with the Romeo-X red dot sight available from Bass Pro-Shops for $999. The variant packaged with the Foxtrot R2 weapon light was too new to find a price for online. However, I found the Foxtrot R2 available for $149.99 at Optics Planet, bringing the total $1148.99. SIG’s price for the bundle should be somewhat lower.

SIG Sauer: www.SIGSauer.com