SIG Sauer P365-FUSE: Full Review

The P365 has become SIG Sauer’s most popular pistol line. The original P365 was introduced in Guns & Ammo’s May 2018 issue, earning Handgun of the Year honors. Its combination of size, weight, caliber, capacity, features, and price quickly shot it to the forefront of most gun owners’ minds. Since then, SIG Sauer has continued to develop and enhance the P365, including the new-for-2024 P365-FUSE.

The P365-FUSE combines the extended polymer grip (and 17-round standard capacity) of the P365 XMACRO with a longer 4.3-inch barrel, plus there are a few unique features. Since this FUSE is a standard model with a polymer lower grip module — not a special Legion model or one sporting the aluminum AXG grip — it costs just a few bucks more than a standard P365. That $729 price includes two spare and extended 21-round magazines. It is optic ready, and versions will be available from SIG Sauer with an electro-optic mounted. Think of the FUSE as the ultimate iteration of the P365. What was once labeled a “micro-compact” is now full size.

(Photo by Mark Fingar)

Why a Full-size P365?

Some will think that offering a full-size version of a micro is unnecessary. So, I need to address the current phenomenon we’ve seen with many micro or subcompacts evolving into full-size models. Expanding dimensions of pistols such as the P365 can make them harder to conceal. For many who would agree, what that tells me is you may not be shooting your pistols as often as you should be. The original P365 was a great gun and an amazing choice for self-defense, but a larger version is easier for most to shoot. The dimensions of the original P365 were an effort to fit as many rounds as possible into a package that measured 5.8 inches in length, by 4.3 inches in height and 1 inch wide. Initially, the stack-and-a-half arrangement in the magazine accepted 10 rounds for the flush-fit and 12 rounds for the extended. And the first model lacked an optic cut to the slide. It was as small as possible while still being large enough to hold on to and shoot decently. The number one criterion for whether a gun is comfortable and controllable enough to shoot fast and accurately beyond 10 yards is grip length. Can you get all your fingers around it? While the first P365 concealed better with the flush magazine inserted, we now know that most P365 users only wanted to shoot it with the extended magazine inserted.

gaad-sig-sig-sauer-365-fuse-03-1200x800 — The stainless slide wears a Nitron finish, locking up with the 4.3-inch carbon-steel barrel. The length extends the sight radius. (Photo by Mark Fingar)

Enter The XMACRO

SIG Sauer designed the extended frame of the P365-XMACRO (Guns & Ammo, November 2022) to be just longer than the P365 with the fingerhook magazine inserted. Not only could just about everyone comfortably grip the gun with their entire hand, but the capacity also increased from 10-plus-one rounds to 17-plus-one. Many of those who I know that carry the P365, who actually shoot their carry guns, predominantly prefer the XMACRO-frame models. They are more than balanced out by the enhanced handling and capacity. The frame isn’t that much longer, and the principal applies to the P365-FUSE. Comparing the FUSE to the first generation P365 — with its flush-fit 17-round magazine inserted — it is only .6 inches longer than the original P365 with the 10-round magazine.

gaad-sig-sig-sauer-365-fuse-04-1200x800 — The green fiber-optic front sight and serrated rear notch are usable given the low cut engineered for electronic optics. (Photo by Mark Fingar)

Why Not a P320?

Between the increased length of the grip and barrel-and-slide assembly, the P365-FUSE is a full-size pistol. Dimensionally, it isn’t much smaller in height and length than the P320. Why would you want the P365-FUSE over a P320? The answer might not be obvious, but with the gun in hand it’s easy to understand.

Compared to any standard, full-size 9mm, the P365-FUSE feels exotic, the slender supermodel of guns if you will. It is significantly thinner than a P320. Though the distance between the front of the trigger and the backstrap is similar, it feels different because the grip is significantly narrower. People with small hands will reach the trigger without needing to adjust their grip while shooting.

gaad-sig-sig-sauer-365-fuse-05-1200x800 — Though the texture on the grip module, magazine, and replacable backstraps are similar, the sides are distinctively cratered. (Photo by Mark Fingar)

The Technical Stuff

The P365-FUSE measures 7.2 inches long, 5.3 inches tall with the flush magazine inserted, and 1.1 inches wide at the slide stop. The slide is just .94 inches wide, and the removable extended steel magazine well increases width to 1.42 inches at the base of the frame. Unloaded, its weight with an empty magazine was scaled at 23.1 ounces

The original P365 had a 3.1-inch barrel. The P365-FUSE has a 4.3-inch barrel. It is made of carbon steel and has a black diamond-like carbon coating (DLC) for a finish. The slide is made of stainless steel, which is given a Nitron finish. It is probably safe to presume that flat-dark-earth (FDE) versions of this pistol will follow, as it has happened with other P365 models. The entirety of this pistol, though, is matte black, except for the flat, matte nickel trigger.

The proportions of the P365-FUSE look perfect, at least to my eyes. The slide is the right length for the grip, and if you’re already carrying an XMACRO inside the waistband (IWB), the extra length of the FUSE will remain hidden inside your pants. However, you’ll notice a difference in handling when it’s time to shoot.

gaad-sig-sig-sauer-365-fuse-06-1200x800 — The P365 trigger remains excellent, featuring a matte nickel finish and a flat face with a hook that breaks at 90 degrees. (Photo by Mark Fingar)

The fiber-optic front sight with black serrated rear was a solid choice. The front sight appears to be a Dawson Precision model, dovetailed into place. It has a green fiber-optic insert, and SIG Sauer provides additional lengths of green and red fiber-optic rods with the pistol should you want to replace or restore the front.

The front sight has a narrow .09-inch width, while the rear notch is .13-inch. This means you get a lot of daylight around that front sight as you’re aligning them, which is just the way I like it. The setup reminds me of the sights I ran on my old competition guns.

The slide is optic-ready, too. The optic cut was made direct-mount for any optic with an RMSc footprint. That includes SIG Sauer Romeo-X Compact optics. Supplied with this pistol for Guns & Ammo’s evaluation was the enclosed-emitter ROMEO-X Compact red dot. The slide is cut low enough that you’ll be able to use your iron sights through the optic window.

The slide has numerous and aggressive cocking serrations at the front and back. There’s also a decorative cut lengthwise near the muzzle. Overall, I think it looks great without being too busy. The only mark on the slide is a small “P365” on the left side.

gaad-sig-sig-sauer-365-fuse-07-1200x800 — In addition to the near-flush-fit 17-round magazine, the P365-FUSE includes a pair of 21-round mags. Why reload so often? (Photo by Mark Fingar)

In the promotional materials for this gun, you’ll see that it uses the LXG Grip Module. The P365 is like the P320 in that the grip is not the “frame”; it is not the serialized part. The P365, like the P320, features a removable stainless-steel chassis within the grip module, and that is the serialized part. The chassis in the P365 isn’t quite as quickly or easily removed as the one in the P320, though, but I’ve done it on my personally owned 1st-gen P365 simply because I didn’t like the near-vertical grip angle on the original gun. (I replaced that grip module with a Wilson Combat version that has a much-improved grip angle.) In fact, both the original P320 and P365 had vertical grips, so it wasn’t long before SIG Sauer started offering its X-Grip Modules for the P320 that provided a more angled grip. Almost every P320 and P365 — apart from the military-contract M17/M18 — sports an X-Grip Module, and that’s what we get with the P365-FUSE. The LXG is the company’s slightly more angled polymer X-Grip module with a modest beavertail and laser-engraved texturing.

The FUSE grip module has the standard fine texturing, but crater-like patches have been added, increasing the aggressive surface of the grip’s sides, frontstrap and backstrap. I liked it for shooting because the gun didn’t move in my hand. I carry a gun with a grip this aggressive, and I can tell you — from personal experience — that you’ll want a t-shirt or something similar between your skin and this grip for comfort.

The pistol is supplied with three interchangeable backstraps. The Medium is installed at the factory. The Small- and Large-size backstraps were found in the lockable hard case; those don’t have the laser-etched texture. The size is marked at the bottom-rear.

gaad-sig-sig-sauer-365-fuse-08-1200x800 — Controls are pronounced on the P365-FUSE, including the takedown and slide-lock levers. The magazine release is reversible. (Photo by Mark Fingar)

The original, smaller P365 had a frame rail. For a time, it was proprietary. SIG Sauer was often the only source for lights and lasers. The P365-FUSE has a three-slot MIL-STD-M1913 Picatinny rail, meaning it will accept pretty much any light on the market meant for a pistol this size. SIG Sauer provided its Foxtrot2R with the pistol for this evaluation, but I confirmed the rail’s utility with a Streamlight TLR-7 . It fit the FUSE perfectly.

At the bottom of the grip, you’ll find a removable magazine well. I was surprised to find that it wasn’t made of polymer (or even aluminum). It’s made of steel. The opening mates well with the beveled opening in the grip module. The magazine well does add about a quarter-inch in length, but it doesn’t protrude farther than the base of the 17-round magazine. It adds less than .2 inches of width to either side of the grip.

While there are neutered 10-round versions for those of you living in states that hate the Second Amendment, the standard version of the P365-FUSE ships with one flush 17- and two extended 21-round magazines. I don’t see anyone carrying this gun with an extended mag inserted, but for a spare magazine, or seemingly non-stop fun at the range, it’s hard to beat running those big sticks.

gaad-sig-sig-sauer-365-fuse-09-1200x800 — The stainless-steel slide features aesthetically pleasing serrations and lighting cuts. Underneath is a Picatinny rail. (Photo by Mark Fingar)

The triggerpull on G&A’s sample FUSE was better than average among striker-fired guns, but that describes the P365 trigger as a rule. After a short takeup, there’s a short, smooth, rolling break. The trigger halted at 90 degrees. Total pull weight was 51/2 pounds. Reset was short and positive.

A brief aside on the enclosed Romeo-X Compact optic supplied with the test gun: SIG Sauer’s line of Romeo-X optics grew out SIG Sauer’s development of the M17/M18 optic for the military contract pistols. They were introduced in 2023. The full-size Romeo-X requires a DeltaPoint Pro footprint, while the Compact model uses the RMSc footprint. It has aluminum and glass construction, a low deck, side-mounted battery, and 20,000 hours of battery life on a CR1632 at the medium brightness setting. It has a 6-MOA dot produced by an enclosed emitter.

gaad-sig-sig-sauer-365-fuse-10-1200x800 — The slide features a low and flared ejection port. The barrel is notched, providing access to inspect for a loaded chamber. (Photo by Mark Fingar)

At the Range

When it was time to test the P365-FUSE I brought my original P365 and oldest son to the range. I was curious how he’d like the two different grips. Harrison is 6 foot, 4 inches tall with size 14 feet and hands to match. I’ve got slender hands that fit into size medium gloves. Harrison could only get half of his pinky on the extended fingerhook basepad of the original P365; it slipped off whenever he started shooting. He also noticed that it had a bit of snap to the felt recoil. Regarding the original P365, he said, “It’s concealable, but it’s not much fun to shoot.” And that’s the point, really, of the FUSE. It’s a complete P365 package maximized for shootability more than concealability. He had no complaints about the FUSE, and neither did I. We spent an afternoon hammering down steel and perforating paper, getting the slide of the FUSE too hot to touch. It shoots like a full-size gun because it is a full-size gun.

The P365-FUSE was a blast. It ran just as well as you would expect from a proven design. I fed it everything, from bargain-priced steel-cased Magtech FMJs to +P JHPs. It ate it all. The pistol has got great sights — irons and optic — and the texturing on the full-length grip kept our hands solidly in place. Even if you’ve got big hands, I doubt you’ll find the grip too small for you. At this point, SIG Sauer appears to offer a version of the P365 to suit every need and taste. If you’re a fan of full-size semiautos as I am, the P365-FUSE is for you.