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  4. Review: SIG Sauer P365 Fuse After 1,000 Rounds

Blending a rich list of features with a thin and very compact frame, the P365 Fuse stands to make full-sized striker-fired pistols an endangered species. 

Table of Contents
 
Overview
The Specs
Features
Trigger
Reliability
Accuracy
Pros & Cons
Conclusion
 

Overview

 

The newest SIG Sauer P365 gets its name, says the company, as it is the "fusion of capability and concealment." This is due to still being carry-sized while featuring all the goodies one could want, including a removable magwell, nickel-plated flat-faced trigger, LXG grip module with interchangeable backstraps, optics-ready (RMSc footprint) slide, easily co-witnessing iron sights, and extended 21-round magazines. 

All this for well under $800.

 

SIG Sauer P365 Fuse 9mm
The new SIG Sauer P365 Fuse. (All Photos: Chris Eger/Guns.com)
SIG Sauer P365 Fuse 9mm
The pistol will be available in at least three different SKUs, including one shipping with two 21-round and one 17-round magazine, another with a Romeo X Compact micro red dot installed (shown above), and a state-compliant (10-round mag) version. 

 

The Fuse comes standard with a DLC-finished 4.3-inch carbon steel barrel, which is over a half-inch longer than the 3.7-inch pipes seen on SIG's P365 XMacro Tacops and P365 XL. This gives the Fuse an overall length of 7.2 inches, making it the longest P365 in the company's ever-expanding universe. 

 

SIG Sauer P365 Fuse 9mm
The P365 Fuse compared to the P365 XMacro Comp. Note the Fuse is a bit longer but remains the same height and width. Both use SIG's 17+1 round flush-fit P365 mags and accept extended magazines as well – into which we will get.
SIG Sauer P365 Fuse 9mm
Another look at the P365 XMacro Comp, shown left, compared to the new P365 Fuse on the right. The XMacro – which has been carried extensively – wears SIG's Romeo X Compact MRD, while the Fuse has the company's new fully enclosed mailbox version of the Romeo Xc. The P365 Fuse uses different iron sights, including a tall blacked-out rear and a Dawson Precision fiber-optic front. 

 

The height, with the standard 17+1 round (same as XMacro) flush-fit mag, is 5.1 inches while the overall width at the thickest point is 1.1 inches. 

SIG's full-sized P320-M17 specs out at 8 inches in overall length with its standard 4.7-inch barrel, a tad longer than the Fuse. However, don't let that one spec confuse you, as the P365 variant is much slimmer, shorter in height, and a half-pound lighter than the service pistol. 

 

SIG Sauer P365 Fuse 9mm
The Fuse compared to the P320-M17. Keep in mind both are shown with 21-round mags inserted and with corresponding versions of the Romeo X enclosed red dot. 
SIG Sauer P365 Fuse 9mm
In terms of comparison, the Fuse is about half an inch longer but remains about as tall and thin as the Springfield Armory Hellcat Pro – when each pistol has its respective 17+1 round magazine inserted. So if you feel the Hellcat Pro is a good size for carry, and are good with adding just a little length, the P365 Fuse is on the menu for sure. 
SIG Sauer P365 Fuse 9mm
Likewise, it is slightly shorter than the Glock 49 (which shares the same length and width as the G17). 

 

For full disclosure, SIG sent Guns.com this pistol for review purposes. All testing was done on this one gun. 

 

The Specs

 

  • Overall length: 7.2 inches
  • Barrel length: 4.3 inches 
  • Sight radius: 6 inches
  • Overall width: 1.1 inches at the widest point over ambi surface controls.
  • Overall height including standard mag: 5.1 ­inches
  • Magazine capacity: 17+1 rounder flush fit, 21+1 extended (ships with each)
  • Trigger pull: 4.8 pounds (10-pull average)
  • Weight, with empty magazine: 23.1 ounces
  • Weight, loaded: 33.3 ounces (with 21+1 rounds of 124-grain 9mm Speer Gold Dot JHP) and Romeo X enclosed optic
  • MRD Optic Footprint: Shield RMSc

 

Features

 

SIG Sauer P365 Fuse 9mm
Disassembly is easy, with toolless takedown via a grip module mounted lever. The P365 Fuse uses an interchangeable serialized FCU, paving the way for future user-level customization via easy slide and grip swaps. The guide rod is polymer and unique to the Fuse.
SIG Sauer P365 Fuse 9mm
The Fuse has surface controls on the left side of the gun, including the downward rotating takedown lever, slide catch, and push-button reversible magazine release, all of which are easy to manipulate. The adjustments on the Romeo Xc are on the same side. 
SIG Sauer P365 Fuse 9mm
The texture on the frame is aggressive – just under the old RTF2 used by Glock in the early 2000s – and aids with retention during the firing cycle. While I prefer a rough texture, falling just under a carpenter's rasp, others may find that it abrades their more sensitive paws. A fix to that would be to either embrace the tactile cheese grater or, as a last resort, sand down said texture like some filthy heathen smashing an altar with a club. Just know that, if this is a carry gun, you may toughen up some belly skin if you don't wear an undershirt. 
SIG Sauer P365 Fuse 9mm
Speaking of texture, the slide serrations aren't just for show. Back in the 20th Century, semi-autos tended to just have a few rear vertical slide serrations added as almost an afterthought. Narrow and set closely together, they were barely useable. Gun makers over the past couple of decades have slanted the serrations, spread them apart, and extended them down the length of the slide. The P365 Fuse has come close to perfecting this gradual evolution and the serrations, especially those forward of the ejection port, are usable even with wet/grimy hands. 
SIG Sauer P365 Fuse 9mm
Turning to the enhanced flared magwell – something more common on competition guns – I'm not sure it is needed on a carry or home protection gun. Nonetheless, it works, didn't come loose in testing, and the wide lip at the bottom helps force the user's grip higher into the beavertail of the frame, almost like a template, to aid in better control. If you don't like it, you can take it off.
SIG Sauer P365 Fuse 9mm
It ships with three mags and extra backstraps. Note the extra backstraps have a smoother texture, which may be a bonus for those who find the LXG to be too aggressive. Also, be ready to use a mag loader to top off those 21s, as the spring is outrageously stout. 

 

The slide is milled to accept any Shield RMSc footprint micro red/green dot optic, which besides Shields and SIG's own Romeo compact lines, will easily accommodate a Burris FastFire C, Viridian RFX, Vortex Defender, Primary Arms Classic, Meprolight MPO Pro-S, Swampfox Sentinel II, or TruGlo XR21. I prefer direct mounts rather than getting adapter plates involved as they have one less failure point while allowing the optic to rest lower in relation to the sights.

 

SIG Sauer P365 Fuse 9mm
We found the Romeo X Compact enclosed to be about the best of SIG's micro red dots to pass through our hands. It feels very Steiner MPS but with sharper glass and a shorter roof. It's rugged, we experienced no shift in point of aim/impact through our evaluation, and the optic remained rock solid across 1,000 rounds. Plus, being enclosed and nitrogen purged, you don't have to worry about fog. Never mind the scratches, which are due to a couple of drops on the range

 

When turning to support, the Fuse is plug and play, so to speak, and it uses standard P365 triggers, a common dovetail and optics footprint, and is reverse-compatible with 17-round mags. Looking for holsters, while it is longer than any other P365 on the market (as of September 2024), almost any XMacro-sized P365 holster with an open bottom should work. 

 

SIG Sauer P365 Fuse 9mm
It fits like a glove in the Galco Corvus modular Kydex holster for the X-Macro. A good thing about the Corvus is that it is adjustable for cant and ride height, has a raised sweat guard, accommodates most suppressor sights and red dots, and is packaged with two sizes of belt slots and can be swapped from IWB to OWB.

 

Trigger

 

The flat-faced trigger of the Fuse is carried over from the P365XL and XMacro and breaks at 90 degrees after moving roughly a half inch at the tip of the bow. The take-up is in the last quarter inch of that travel, and the break hits at about 4.5 to 5 pounds in our tests. 

 

 

I find the trigger reset on P365s to run a little long, which is probably a throwback to cutting my teeth on single-action hammer-fired pistols. To wit, a curious malfunction of the Fuse that I noticed across range visits was the proclivity of the trigger to go "dead" sometimes when pinning it in slow fire and riding the reset – a technique that is not advisable in field use – no doubt due to the user not allowing a full reset to engage with the striker. The solution to that is not to pin the trigger. 

 

Reliability

 

The Fuse has been on the market for a few months and there have been some persistent reports from the field of some users having issues with their new guns experiencing a failure to go into battery and just general failures to properly feed and cycle. Many of these users followed up with redemption videos once the guns came back from SIG after warranty work. 

We didn't have quite the same experience, logging twin FTFs early in the 1,000 rounds we ran in the Fuse. That and the user-fault trigger reset issue described in the trigger section above were the only notable malfunctions. 

With that in mind, always vet any gun meant for personal protection through several range trips to verify it is going to perform well before trusting it. 

 

SIG Sauer P365 Fuse 9mm
The ammo used for testing when it came to practice loads included Federal's 115-grain Syntech, 147-grain Gold Medal Action Pistol, 124-grain Syntech Training Match, and 115-grain Train & Protech JHPs. This was blended with some Blazer Brass 115 and some Wolf gray/green case. Personal protection loads included Federal Punch 124 and Speer Gold Dot 124 JHPs along with a handful of loose Noslers. 

 

We did note a common issue seen with P365s – or any micro 9 for what it's worth – in that the pistol heats up rapidly in long-range sessions with back-to-back use, becoming uncomfortably hot to the touch on the trigger pack and controls after a couple of hundred rounds. 

 

Accuracy

 

The P365, after verifying the point of aim/impact of the factory-installed Romeo Xc red dot, proved exceptionally accurate. We didn't bother measuring groups, as the gun tended to easily eat the heart out of every target out to 15 with no problems and keep it in the center to 25 when shooting in standard offhand stances. 

 

SIG Sauer P365 Fuse 9mm
The Fuse is accurate. 

 

Pros & Cons

 

Pros

  • Great ergonomics
  • Good magazine capacity with two different sizes supplied 
  • Capable of easy upgrades
  • Common MRD footprint
  • Holsters available 
  • Accurate

Cons

  • Pushing into a more full-sized envelope than previous P365s (which is kind of the whole point)
  • Mixed reliability reports on some early models
  • Magwell may not be for everyone

 

Conclusion

 

The P365 Fuse seems to be an "I wish" gun. In other words, meant for those curious who picked up a standard P365 and said, "This is great, I just wish it..." were bigger, had a higher capacity, didn't have a compensator or ported barrel, etc. then never had their specific itch scratched by the follow-on P365 X, P365 XL, P365 SAS, P365 AXG, or P365 XMacro.

It has grown to the point of becoming almost a full-sized gun akin to a P320 but a lot lighter and more svelte in the hand and on the body. The Fuse is so much larger that it is a P365 intended to be used in practical competition. If SIG hadn't put its old P365 EDC Championships in the rearview I would think the Fuse was designed with those matches in mind. On the upside, it straddles the fence between being a good size for a carry gun while still being able to double as a full-size "bedside" gun for home defense as well – especially with the accessory rail for WMLs. 

 

SIG Sauer P365 Fuse 9mm
When paired with a good holster, the Fuse can easily be carried. In an arrangement such as in the above picture, you get the ability to cut the profile a little by using the flush-fit mag with a 21-rounder (or two) as a backup. The white light is a 33,000 Candela SIG Foxtrot EDC that has gotten a bit of carry. 

 

In boxing terms, the Fuse is like a Cruiserweight fighter who has bulked up to stand in the Heavyweight class. Is that bad? Well, some of the best heavyweight title holders were cruisers with good technique that moved up – guys like Evander Holyfield and David "Haymaker" Haye. 

Is the Fuse a Holyfield? It shoots well. It feels great. Purists who were satisfied with legacy P365s will probably hate it, saying it got away from its Cruiserweight (or even Middleweight) roots and SIG has lost sight of the prize. However, those looking for a more capable fighter wouldn't be ill-served with the Fuse. It could be a champ.  

One interesting takeaway on the Fuse is that, with its slim grip and profile, it could be the perfect gun for those with smaller or medium-sized mitts who have issues with full-sized pistols. 

With that, it could be the people's champ. 

 

SIG Sauer P365 Fuse 9mm
Depending on the model, the SIG Sauer Fuse has an ask between $1K with the Romeo X Compact included to the low $700s without. 

 

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