Sig Sauer P365 Models: History, Evolution, & Why They’ve Remained #1

The popularity of the Sig Sauer P365 at SHOT Show 2018 was a clear indicator it would succeed…and it has.

In 2018 and 2019, it was the number one selling gun, according to American Rifleman.

But where did the P365 come from, and how has it evolved and changed since its introduction?

Keep reading as we detail its origin and evolution.

What Is the P365?

The Sig P365 is a 9mm, micro-compact firearm that uses a striker-fired system and a polymer frame. While those are the basics of the gun, they don’t tell the whole story.

Sig innovated in two ways with the P365…

The first was the magazine design, and the second was the fire control unit.

Sig cooked up a magazine that seemingly mixed a double-stack with a single-stack magazine. It appears to be a single-stack at the very top but flares outward into a standard double-stack setup.

This allowed the gun to remain thin and somewhat short while still packing 10 rounds of 9mm.

Sig started the fire control unit craze with the P250.

An FCU is a chassis that holds 99% of the internal parts and wears the serial number. By law, it’s the actual firearm.

A removable FCU allows the user to switch frames, slides, and calibers without the need to order parts that are considered additional firearms.

It opens up a crazy level of modularity.

When you put all this together, the P365 stands out as one of the most innovative carry guns ever made.

Sig Sauer P365 Origin: Where It Started

In 2018, Sig had the P290RS and the P938, but they didn’t have a striker-fired micro-compact pistol.

“Like most new ground-up projects at Sig Sauer, there was an opportunity in a certain section of the market that our company did not have an ideal product for. In this case, it was the micro-compact striker market,” Phil Strader, the Director of Firearms Product Management at Sig Sauer, told Pew Pew Tactical in an interview.

He continued, “Our goal became clear. To produce an ergonomically superior pistol that checked all the boxes for size while surpassing everyone in capacity.”

“This was my first project after being hired at Sig Sauer, and we commenced to designing a pistol that people serious about CCW would want to carry every day of the year without sacrificing capabilities such as accuracy, shooting comfort, and capacity.”

According to Strader, it took two years of product design, development, and testing.

The biggest challenge was “making a 10-round magazine fit in a 1-inch wide, 4.3-inch tall gun. Making it work with a grip module AND accommodating a removable FCU without losing ideal ergonomics was also a tall order.”

“Magazine capacity was the highest priority. Making it modular was a threshold of development, provided it wouldn’t sacrifice capacity.”

Law Enforcement and the P365

Since the P365 hit the market, it’s been a big winner in the civilian concealed carry market, but that’s not all.

In fact, it’s become quite popular with law enforcement as well.

In some towns, it’s the firearm issued to investigators and plainclothes personnel.

The Miami Beach Police Department adopted the weapon in 2021 for concealed carry and administrative roles.

In Pasco County, Florida, the P365 serves as a backup and admin gun.

The Indiana State Police adopted the pistol as a backup firearm, and so did the Sumter Police Department in South Carolina.

It has also been approved for use with the Chicago Police Department and Hayward Police Department out of California.

Sig Sauer P365 Models Explained

When you top the sales charts for two years in a row and sell more than 2 million pistols, you don’t just rest on your laurels. You evolve — and Sig did just that.

They pushed the P365 to new levels and pumped out accessories. So let’s take a look at some of the models with the P365 name.

P365XL

Sig stretched the P365 into the P365XL.

This involved lengthening the barrel from 3.1 to 3.7 inches and increasing the height from 4.3 to 4.8 inches.

The P365XL shipped with 12-round flush fit magazines, meaning the regular 10-rounders from the P365 wouldn’t fit.

They also made the P365XL optics ready for compatibility with optics that used the Shield RMSc footprint.

Unsurprisingly Sig’s own Romeo Zero fits perfectly. Sig also equipped all XL models with the flat-faced trigger.

Alongside the P365XL, Sig released a 15-round extended magazine with interchangeable baseplates for use in the P365 and P365XL.

Check out our full review of the XL here.

P365 SAS

Following the success of the P365, Sig released a SAS (Sig Anti Snag) mode.

The SAS configuration wasn’t new. Sig’s done plenty of firearms in the past in the SAS configuration, but the P365 SAS took it a step further in snag-proofing the design.

Sig softened the corners as usual and smoothed things out to make it easy to draw from concealment. The company also lopped off the sights and replaced them with a three-dot rear sight that’s embedded and flush with the top of the slide.

Sig then trimmed off the controls, including the slide lock and takedown lever.

The slide lock sits flush with the frame, and the takedown lever is a simple flat-head design that can be manipulated with a cartridge edge, coin, or similar object.

To finish things off, Sig ported the barrel and slide for better recoil control. The company later offered a non-ported version of the SAS for those who wanted to avoid the larger muzzle flash and blast.

Johnny B took the P365 SAS for a spin. Check out his review here or watch the video below.

P365X

2021 was a rough year. COVID prevented SHOT Show, and the industry didn’t get a ton of big reveals as a result, but Sig did unveil the P365X…just quietly.

The P365X used the XL frame with a P365 standard slide. Its slide came optic-ready, and the gun used a flat-faced trigger.

Initially, it was paired with the Romeo Zero but would later be offered without it.

Oddly, Sig never released a P365L with the shorter frame and longer slide combo, but you can swap slides and frames to make this combination yourself if you wish.

P365-380

Sig unveiled the P365-380 in 2021, but it didn’t see a full release until 2022.

The P365-380 is predictably a .380 ACP version of the P365.

It’s the same size and capacity with seemingly the same grip module and similar magazines with nothing more than an insert to compensate for the slight length difference.

The P365-380 offers a lower recoil variant of the P365 that’s about 2 ounces lighter, but other than that, it’s the same gun as the P365.

P365XL Spectre Comp

The Spectre line of Sig firearms is high-quality, heavily modified guns from Sig’s custom shop.

Sig’s Spectre Comp P365XL features several fancy features we don’t see on stock P365XL models, including a distressed finish, unique cutouts on the slide, a gold barrel, and a skeletonized flat trigger.

It’s a gorgeous gun, almost too pretty to conceal…almost.

Sig also produced a Spectre Comp P365XL with an integrated compensator and a non-skeletonized flat trigger.

The Spectre models represent the top of the line of Sig’s P365 models, and they are beautiful guns — almost BBQ gun territory.

Sean took this one and the XL for a whirl, so read the review or catch the video below.

P365 X-Macro

In August of 2022, Sig once again shocked the gun world.

They lengthened the grip even further than the XL model, making the gun 5.2 inches tall. The gun was widened, but only a minuscule amount, to 1.1 inches.

What did this achieve? A whopping 17-round capacity.

Sig applied its magazine technology to a larger gun but made sure it retained the thin profile and ergonomics that made the P365 successful.

The X-Macro comes with an integrated compensator and a flat-faced trigger. It’s also optics-ready.

A few new things specific to the X-Macro were the addition of interchangeable backstraps and a standard 1913 Picatinny rail in place of Sig’s proprietary rail on previous models.

With a design concept so successful, why not push the envelope?

The X-Macro does just that and may very well represent the next step in the future world of carry pistols.

Check out our video review below or read the review here!

What Makes the Sig Sauer P365 a Good Gun

What made the P365 a “good gun” by industry standards?

The most obvious answer is that the P365 did something no other gun on the market did, with the exception of the Kel-Tec P11.

They packed 10 rounds into a gun that, by the specs, should hold six or seven rounds at best. That capacity was the draw, but the staying power is that Sig made a genuinely good gun.

Sig designed the gun to be more than a gimmick and exemplified the concept of brilliance in the basics.

Ergonomics were spot on; the gun was comfy and fit a wide variety of shooters. Sig tossed in a nice trigger, solid high visibility day and night sights, and ensured it was reliable (a few early road bumps withstanding).

Oh, and Sig pumped them out at an affordable price point. They competed with guns from Glock, Springfield, Ruger, and Walther but offered more rounds per magazine than the competition.

Of course, offering an evolving product line helped, and having magazines and holsters from the get-go helped. The FCU system allowed an aftermarket of grip modules to flourish. Wilson Combat, Gray Guns, and many more produced grip modules of various types.

Heck, a company called Icarus Precision even produced an all-metal grip module.

In fact, the aftermarket hit the gun hard.

Sig’s choice to use proprietary rail instead of a standard Picatinny rail seemed silly, but nevertheless, numerous companies produced lasers and lights for it.

Most notably, Streamlight made the TLR-7 SUB, and Surefire made the XSC as micro-compact lights.

We saw various barrels, triggers, and optics choices expand — and the Sig P365 embraced all of them. It is an innovative design, a solid performing pistol, and boasts an expansive aftermarket.

The P365 certainly succeeded on these merits, and the market noticed.

Who doesn’t make a micro-compact with a capacity of at least 10 rounds these days? Hell, even Kimber got in on it!

Final Thoughts

Sig spawned an entirely new genre of pistols. So what does the future hold for a brand that seems to constantly churn out new products?

Is there anything coming down the pipeline?

Sig’s answer…”Yes…and No.”

It seems like the story of the P365 isn’t over. What will we see next? Let us know in the comments below! You can also take a look at some of the competition and the other micro-compacts that the P365 spurred in our article covering the 7 Best Micro Compact 9mm Handguns.