Expertly blending the light handling of Sig’s popular P365 compact with the longer barrel and high-magazine-capacity shades of the big boy P320, the all-new P365-FUSE sits in the enviable “Goldilocks Zone.”

by Rob Reaser

Anyone who has even a passing familiarity with Sig Sauer’s P365 and P320 series of striker-fired pistols knows that the company offers so many flavors of these uber-popular handguns that it’s tough to keep track of them all. Within the generalized categories of compact (P365) and full-size (P320), Sig presents size options, slide and grip module configurations, color choices, and even specialty guns like the Custom Works series. Yet with all the variations, the core definer is size. If it’s compact concealability you want, the P365 series is your go-to. Prefer a fuller grip and an overall heftier nature in your defensive pistol? The P320 delivers.

I’ve been shooting both variants the last few years — a P365XL Spectre and a P320-X Compact — and have come to appreciate their reliability, ergonomics, and inherent accuracy. Of the two, I understandably find the P365 to be the finer choice for EDC because it is easier to carry concealed and is a comfortable shooter. And although it checks all the boxes for a CCW qualifier, the grip is just a hair short of my ideal. As for the P320, while it offers greater range confidence thanks to the larger grip, the overall width and length of my X Compact has always seemed slightly disproportionate in my hand. Nevertheless, I enjoy shooting it and carrying it on occasion.

First Test: Sig P365 Fuse 9mm

So, imagine my excitement when I was invited for a backroom sneak peek at the NRA show of the next P-series model from Sig that, as my host explained, bridged the gap between the P365 and the P320. My first response when I was handed the gun and wrapped my hands around the familiar LXG grip was simply, “Ooooh…”

Although I am loathe to tap the cliché, it perfectly describes my first blush impression of this newest offering from the Sig Sauer skunkworks: not too big, not too small…just right.

The Sig P365-FUSE

First Test: Sig P365 Fuse 9mm

Anchored somewhat firmly in the parent P365 design camp, the P365-FUSE is aptly named as it is a genuine fusion drawing on the best attributes of the compact P365 and the notably larger P320 series.

The gun comes out of the gate in two model configurations: the P365-FUSE and the P365-FUSE ROMEO-X. Both feature slides cut with an RMS-c footprint; however, the P365-FUSE ROMEO-X includes the ROMEO-X Compact red dot as part of the package.

First Test: Sig P365 Fuse 9mm

The 30,000-foot view of the P365-FUSE boils down to this. The pistol retains the slender width of the P365 while serving up a longer grip that accommodates a 21-round capacity magazine and a longer barrel/slide configuration for an increased sight radius and enhanced accuracy potential.

First Test: Sig P365 Fuse 9mm

Although the P320-X Compact (right) skews this visual comparison because of its reduced slide/barrel length when compared to the full-size P320, you can see how the P365-FUSE sits comfortably in the middle of this and this P365 XL Spectre (left). The P365-FUSE holds to the P365 overall width of 1.1 inches verses 1.3 inches for the P320. The FUSE slide is also smaller in height and width than the P320.

Now that we see how the P365-FUSE compares to the more girthy P320 series, let’s have a more apples-to-apples comparison between this new crossover pistol and its P365 progenitor.

First Test: Sig P365 Fuse 9mm

At first glance, it is evident that both handguns exhibit linked DNA. Note the similarities in the grip module contours, the deep beavertail grip, and the close design cues of the slide serrations. The overall widths are identical.

That is where the similarities end.

First Test: Sig P365 Fuse 9mm

The P365-FUSE is all about delivering ample firepower in an easy-to-carry and concealable package. The “base” magazine included with the handgun is 17-round unit that offers a flush fit to the bottom of the grip. That is fairly impressive given the P365-FUSE’s trim grip profile. If you want more rounds on board, though, the pistol also comes with two 21-round mags.

I found the extended magazines to be welcome on the range, as they significantly increased the time spent between reloads. On the personal defense front, few would argue the value of basically doubling fire capacity (comparing to the issued 12-round mags of my P365 XL Spectre).

The 21-round magazines offer no handling hiccups in drawing or firing the gun. The additional 1.25-inches of magazine protruding out of the grip may, though, be problematic for some clothing configurations if absolute concealment is a priority. Given that so many of the violent encounters we hear about today involve multiple perpetrators/attackers rather than the solitary stick-up goons of yesteryear, a fuller magazine with some minor printing is a tradeoff I’ll gladly accept.

First Test: Sig P365 Fuse 9mm

Sig fans are well-familiar with the company’s LXG (laser-engraved X-grip). I’ve found it to be one of the best blends of traction and comfort on the market. It doesn’t chew up your palm like some of the more aggressive patterns, yet it provides ample grip even when your hands are sweaty. Combined with the finger groove behind the trigger guard, the magwell flare below, and the high and deep beavertail, the hand locks easily into a solid and well-aligned firing position.

First Test: Sig P365 Fuse 9mm

The P365-FUSE comes with a removable magwell flare. This is a good thing, I feel, because the length of the 21-round mag demands a bit of “funnel” during rapid mag changes. Most standard-size mags allow your index fingertip to touch the tip of the exposed cartridge when drawing from a mag pouch, and that is a big help in aligning the mag for insertion. People with small- or medium-size will lose this ability with a long mag, so the guiding function of the magwell flare helps mitigate potential fumbling during a reload.

First Test: Sig P365 Fuse 9mm

Removing the magwell flare allows you to swap backstraps on the P365-FUSE. Three profiles are included with the gun: small, medium, and large. I found the large backstrap, with its more pronounced palm swell, to provide the ideal grip and wrist angle. To swap the backstraps, simply remove the magwell flare and push out the backstrap retaining pin. The backstrap can then be slid off the grip module.

First Test: Sig P365 Fuse 9mm

One of the many things I absolutely appreciate about the P365-FUSE are the deep serrations on the front and back of the slide. Too many slides have little more than suggestions of serrations, and that makes the slide difficult to manipulate if your hands are especially dry or sweaty. These serrations, though, run deep and deliver a sure grip when charging or correcting a malfunction (something I never experienced with the P365-FUSE during testing, by the way).

Note that the P365-FUSE grip module incorporates a 1913 accessory rail with ample room to secure a light or laser.

Note also the fiber optic front sight. Made by Dawson Precision, it comes installed with a green FO element that can be swapped with an included red element if you prefer, or with a replacement green element.

First Test: Sig P365 Fuse 9mm

The rear sight is of the square notch variety. It presents a clear and crisp sight picture and has rear blackout serrations to eliminate glare.

You may have picked up on the fact that these open sights seem unusually low for a sight system intended to be used on a pistol with a red dot. That’s because the low, super-compact profile of the Sig ROMEO-X sits, as the company characterizes it, “on the deck” of the slide. By mounting so low in the slide cut, the ROMEO-X Compact allows standard-height open sights to co-witness with the red dot. What’s more, this low profile doesn’t mean the standard-height open sights become crowded in the sight picture.

First Test: Sig P365 Fuse 9mm

As you can see here, the open sights are clearly and readily visible. If the red dot were turned on, it would be sitting right atop the front sight, making for a perfect 1/3 co-witness. Another advantage here is that the lower open sight height means you have full backup sight capability with less snag potential compared to the typical suppressor-height or MOS-height open sights.

Overall, the P365-FUSE ROMEO-X offers a tidy and efficient sight system that won’t let you down.

First Test: Sig P365 Fuse 9mm

The P365-FUSE trigger is standard fare for the P365 series — flat faced with a middle-of-the-road performance. The wall is distinct enough, but I’ve never been a fan of the somewhat mushy feel. No big kudos here, but the nickel-plated trigger shoe is cool.

What I can say is that whatever I may feel about the trigger, it never seems to get in the way of downrange accuracy.

First Test: Sig P365 Fuse 9mm

Of course, many factors play into accuracy potential — close tolerances and precision construction of moving assemblies, good engineering, and a good barrel. The P365-FUSE (shown left) measures 4.3 inches. It is made of carbon steel with a DLC finish and is just over half an inch longer than the P365 XL Spectre barrel at right. A half-inch may not sound like much, but in a pistol, that can have a big influence on accuracy.

First Test: Sig P365 Fuse 9mm

Range day for the P365-FUSE was quite enjoyable given that I partook during the middle of a massive heat dome that had settled over the eastern U.S. Despite the jungle heat producing sweaty hands and salt-stung eyes, the pistol proved its mettle. The ergonomics are spot-on for rapid sight acquisition and alignment. With its slim profile and low barrel bore axis, the P365-FUSE jumps quickly to the target. Fire and it’s right back on point, ready for the next round.

First Test: Sig P365 Fuse 9mm

Burning through my stash of Fiocchi Range Dynamics 124-gr. FMJs, I tested the P365-FUSE for accuracy on the bullseye targets and practical engagement on the silhouettes. With the ROMEO-X zeroed, it was all point-of-aim/point-of-impact. The gun ran flawlessly, cycling mag after mag without a stumble.

First Test: Sig P365 Fuse 9mm

I don’t want to say that I shot the new Sig P365-FUSE with results as good as that of my sturdy EDC 1911, but if I’m honest with myself, it’s a close race. It will take many more hours on the range before I might contemplate a status change. Then again, with triple the firepower on hand, the P365-FUSE makes a compelling argument.

P365-FUSE ROMEO-X Specifications

  • Caliber: 9mm
  • Capacity: 21 / 17
  • Overall Length: 7.2 inches
  • Overall Height: 5.7 inches
  • Overall Width:  1.1 inches
  • Barrel Length: 4.3 inches
  • Sight Radius: 6.0 inches
  • Optics Slide Cut: Compact
  • Weight (w/magazine): 24.8 ounces
  • Price: as low as $699.99

First Test: Sig P365 Fuse 9mm

ROMEO-X Compact Red Dot

  • Footprint: P365 and Compact
  • Magnification: 1x
  • Reticle: 2 MOA Dot / 32 MOA circle
  • Objective Lens Diameter: 24 mm
  • Illumination Settings: 12 daytime, 3 night vision

Shoot On Editor-in-Chief Rob Reaser is a lifelong outdoorsman, former magazine editor, columnist, and contributing editor to numerous national publications in the automotive and outdoor segments. He has also authored and co-authored several DIY gun building books. His shooting and hunting passions cover everything from traditional archery and big-game bowhunting to the latest in handguns, rifles, and reloading. Rob has a troublesome habit of pulling guns and things apart to see how they work; occasionally, he manages to get them back together...

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