A Practical Review of SIG SAUER's 365 FUSE

SIG SAUER's latest P365 9mm variant blends concealment with shootability.

January 09, 2025 By Richard Nance

Affiliate Disclosure: This page contains affiliate links. We earn from qualifying purchases.

In 2018 SIG SAUER’s P365 redefined the concealed-carry gun with best-in-class capacity, premium sights, and a better trigger than you’d expect on a striker-fired micro-compact 9mm. Since I first got my hands on one, the P365, in one of its many forms, has been my go-to carry gun. In addition to the original, I own an SAS, an XMACRO Comp, and a Wilson Combat WCP365X. In all, there are 196 variations of the P365, which speaks to its popularity.

Developing the highest capacity micro-compact pistol on the planet gave SIG SAUER the opportunity to flex its engineering muscles and prompted other firearms manufacturers to follow their lead. As others struggled to catch up, SIG SAUER expanded the P365 lineup to include progressively larger models while staying true to the P365 lineage. The latest P365 is called the FUSE. As the name implies, this do-it-all pistol was designed to be a fusion of shootability and concealment. Its carbon-steel, DLC-finished, 4.3-inch barrel is the longest of any compact pistol in its class, and its 21+1 round capacity is the highest of any P365.

Larger than the original P365, the new FUSE version is 7.2 inches long, 5.1 inches tall, and 1.1 inches wide. Weighing in at 23.1 ounces unloaded. (PHOTOS BY YAMIL SUED)

The FUSE’s polymer LXG (laser engraved X-grip) is a variant of the XMACRO grip module. It features a unique stippling pattern that locks the pistol into your hand for optimal control. Small, medium, and large interchangeable backstraps allow you to tailor the grip to your hand. The FUSE shoots like a full-sized pistol, but its slim profile conceals easily.

The FUSE measures 7.2 inches long, 5.1 inches tall, and just 1.1 inches wide. That’s considerably larger than the original P365, which is still a great option when concealment is the primary focus. But not everyone wants a micro-compact pistol. While they are easy to conceal, their shorter grip, shorter sight radius, and light weight make them harder to shoot. The FUSE’s longer barrel and slide equate to a 6.0-inch sight radius, which enhances the accuracy potential of its fiber-optic front and all-black rear sights. But these days, pistol optics are more popular than ever.

Fiber Optic Front Sight — The pistol’s front sight is a fiber-optic type. (PHOTOS BY YAMIL SUED)

Optics simplify aiming by allowing you to overlay the dot onto the target, rather than aligning front and rear sights. With practice, most shooters will shoot a pistol faster and more accurately with an optic. Like all other P365s in production, the FUSE is optic ready. It uses the Shield RMSc footprint, or what SIG SAUER refers to as their “compact” optics cut. The FUSE can be purchased with a factory-installed ROMEO-X Compact optic. (See the accompanying sidebar for more about that optic.)

Rear Sight and Optic — The pistol’s rear sight is all black, and the face has fine grooves. (PHOTOS BY YAMIL SUED)

While an optic cut is nothing new to the P365, the FUSE’s stainless-steel, Nitron-finished slide has been redesigned, making it easier to rack. Each side features six deep, forward-sloping grooves, both front and rear. The front grooves extend to the top of the slide, while the rear grooves extend to the bottom. Although the angled grooves give the FUSE a distinctly different look, they aren’t merely cosmetic. Their depth and width facilitate a sure grip when racking or conducting a press check.

The LXG grip module’s undercut trigger guard and beavertail help the shooter achieve a high grip for optimal recoil control. Backstrap interchangeability means you can alter the palmswell for comfort, control, and trigger reach. The smooth, recessed section below the trigger guard and on either side of the grip, behind the trigger guard, ensures grip consistency.

The FUSE’s removable magwell funnels magazines into the pistol for easier loading, without being overly bulky as with many competition-oriented pistols. That said, the magwell could make the FUSE more difficult to conceal under a garment. With a jacket, a sweatshirt, or even a heavy shirt, I would leave the magwell on because in addition to making the FUSE easier to load, it acts like the pommel of a sword to keep your hand from sliding down the grip. However, if I were concealing the FUSE under a t-shirt, I’d ditch the magwell in favor of concealability. It’s nice to have options.

fuse magwell — The FUSE’s removable magwell funnels magazines into the pistol for easier loading, without being overly bulky. (PHOTOS BY YAMIL SUED)

The FUSE’s oversized, grooved slide catch protrudes just enough to actuate with either thumb without getting in the way when shooting. With the slide to the rear, depressing the slide catch is more efficient than racking the slide to chamber a round. The time saved can help you win a match or, more importantly, prevail in a self-defense situation. The three-slot 1913 accessory rail enables you to mount a light, a laser, or a combination thereof. These days, many pistol lights have a built-in laser. While a laser is overkill if you’re running an optic, it provides the same aiming point as an optic, giving you an edge over iron sights. While a laser is redundant if you’re using an optic, a light is an excellent addition to a defensive pistol.

A handheld flashlight will be a better option in certain scenarios, but having a pistol-mounted light ensures that whenever you’re armed, you have a light source at the ready. A pistol light like the SIG SAUER FOXTROT2 allows you to illuminate while maintaining a two-handed shooting grip, albeit slightly modified. With two hands on the gun, you have far better recoil control than if you were using a handheld light. Accessories can’t compensate for a bad trigger. Fortunately, the FUSE has a good one. The nickel-plated, flat-faced X-series trigger breaks at 90 degrees, eliminating overtravel. The trigger pull on my test gun averaged 5.5 pounds according to my Lyman digital trigger pull gauge. There was minimal take-up before the wall, then just a bit of grittiness to get past it. Reset was short and easily discernible, thanks to an audible click and a perceivable bump.

fuse trigger — The author says the pistol’s nickel-plated, flat-faced X-series trigger is a good one. The trigger pull averaged 5.5 pounds, take-up was minimal, and reset was short. (PHOTOS BY YAMIL SUED)

Shooting Impressions

I shot the FUSE at the SIG SAUER Academy during SIG’s NEXT event, where the pistol was first introduced. As soon as I picked it up, I was impressed. The aggressive grip texturing and ergonomics felt better than any P365 I’d shot before. In fact, I can’t say a pistol has ever felt better in my hand. With the ROMEO-X Compact optic, I was able to consistently make short work of the 6.0-inch plate rack. The FUSE is well balanced. Recoil is minimal, and it’s fast on target, whether from a low ready position or transitioning from one plate to the next.

The grooved, triangular magazine release was easy to reach and depress with my thumb. Reloading was a cinch with the magwell, especially when loading 21-round magazines where there’s ample gripping surface and the baseplate extends well below the bottom of the pistol. Truly a crossover pistol, the FUSE could fill the bill for action pistol competition, home defense, concealed carry, and even as a police duty sidearm, particularly for smaller-handed officers who might struggle to control a thicker pistol.

Further testing at my local range reinforced my first impressions of the FUSE. It ran without a hitch with ammunition ranging in weight from 115 grains to 135 grains, including both full metal jacketed bullets and hollowpoints. Oddly, the FUSE wouldn’t chamber Hornady’s 124-grain Black XTP load. This served as a good reminder that not all firearms and loads are compatible. Federal’s 115-grain Train + Protect Versatile HP ammunition proved to be the most accurate and achieved the highest velocity during testing.

fuseaccuracy — (Photo Provided by Author)

The higher velocity generated by the FUSE’s longer barrel will likely translate to better penetration and superior ballistic performance compared to a shorter-barreled pistol, yet the longer barrel and slide make the FUSE no harder to conceal than a shorter-barreled pistol, especially when carried inside the waist where the slide tucks into your pants.

Speaking of concealed carry, the Alien Gear Photon Holster ($45) can be purchased on the SIG SAUER website. The Photon can be configured for inside the waist or outside the waist carry. Given the popularity of the P365 platform and the FUSE’s presumed universal appeal, I suspect there will be plenty of holster options in the coming weeks.

The FUSE comes with two 21-round extended magazines and a 17-round flush-fitting magazine. The 17-rounder is more easily concealed yet still offers industry standard capacity. (For states with magazine capacity requirements, the FUSE is offered with three 10-round magazines.) When concealment is less of an issue, a 21-round magazine and the magwell will afford you maximum capacity and performance. When concealment is paramount, ditching the magwell and opting for the 17-round magazine is the way to go.

The FUSE is about as close as you can get to a one-size-fits-all pistol. It can be purchased with a factory-installed ROMEO-X Compact optic, or you can add your own RMSc-footprint optic. If you’re old school, the stock sights will suffice. More than perhaps any other pistol, the FUSE bridges the gap between concealment and shootability. It’s neither the biggest nor the smallest, but it can handle just about anything. The FUSE is a solid choice for the person who will own only one pistol. I have several pistols, but the FUSE, topped with a ROMEO-X Compact optic, will be my primary concealed-carry option for the foreseeable future.