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SIG Sauer P365 Pistols: 9mm vs .380 ACP

SIG Sauer downsized its P365 pistol, adding a new chapter to the age-old 9mm vs .380 ACP debate. Is the P365-380 enough gun?

SIG Sauer P365 Pistols: 9mm vs .380 ACP

SIG Sauer’s downsized P365 pistol adds a new chapter to the age-old 9mm vs .380 ACP debate. Is the P365-380 enough gun? (Photo by Muzzle Flash Media)

The SIG P365 platform has been written about ad-nauseum. In fact, I didn’t even want to write this review because my mind was made up that the only acceptable chambering for the P365 was 9mm. I was wrong, the P365 in .380 is a great little gun.

SIG Sauer P365-380 left side.
Visually, the P365-380 is identical to its 9mm counterpart. (Photo by Muzzle Flash Media)

Externally, the P365-380 is identical to the 9mm version. In fact, much like a 9mm 1911, it uses the magazines of its larger sibling, modified with a block along the back to position the cartridge accordingly. In some pistols, this is problematic because the cartridge has to “jump” into the chamber, which can cause feeding issues. With the P365, the cartridge has a straight shot to the chamber, so there is no issue with feeding. Although my stash of .380 is considerably smaller than my 9mm supply, I was still able to put 400 rounds through the pistol for the review. I had two failures to go into battery in the first 50 rounds, but after that there were no further malfunctions.

SIG Sauer P365-380 right side.
The P365-380 handles well thanks to its ergonomic grip frame, full-diameter texture, and cocking serrations fore and aft. (Photo by Muzzle Flash Media)

Dimensionally, the P365-380 pistol is 5.8 inches long, 1 inch wide and 4.2 inches tall. The polymer frame features the excellent ergonomics that the P365 is known for, placing the shooters hands high up on the gun due to the shape of the backstrap and the undercut trigger guard. If the P365 was any smaller, it would be difficult to control and uncomfortable for many shooters. I generally prefer the slightly larger P365 XL frame, but the P365 frame is very shootable and with the introduction of the .380 chambering, it’s even more controllable.

SIG Sauer P365-380 barrel.
The .380 ACP chambering is new for the P365 line, and the pistol's barrel is marked accordingly. (Photo by Muzzle Flash Media)

Sometimes, as shooters, we forget that not everyone fits the high-speed operator or gritty frontiersman ideals – most of us are mere mortals, despite our go-fast videos on social media. In the real world, many people have hand strength issues or suffer from arthritis, and for those people the 9mm can be painful to practice with in a gun the size of the P365. The .380 solves that problem by giving them less recoil to deal with. Of course, with less recoil comes less terminal performance, and this is where the argument against the .380 ACP has some relevance.

SIG Sauer P365-380 disassembled.
Disassembly follows the familiar process and the gun breaks down into the slide assembly, frame assembly, barrel and recoil spring. (Photo by Muzzle Flash Media)

As our collective understanding of ballistic performance increases, we are seeing that in order to perform in a manner consistent with its intended purpose, a cartridge must, above all else, penetrate to a depth of at least 12 inches through bone, muscle and liquid. Most serious ballistic studies have shown that the modern 9mm defensive loadings hit the sweet spot of penetration, expansion and weight. Smaller, faster projectiles don’t do nearly as well unless they’re moving at rifle velocities, which can’t happen with pistol-length barrels. On the other hand, larger, slower projectiles like the .45 ACP deliver similar ballistic performance but with more recoil, less magazine capacity and more wear on the gun. Although sycophants of any rounds will readily spew their anecdotal evidence to anyone that cares to listen, most ballistic and defense experts have come to the same conclusion: The difference in handgun-caliber effectiveness is statistically irrelevant. If the projectile expands to .4 inches, weighs about 100 grains, and penetrates at least 12 inches, the result of the handgun round will be pretty similar, regardless of designation.

SIG Sauer P365-380 and <a href='' alt='Hornady' title='Hornady' target='_blank'>Hornady</a> Critical Defense.
Personal protection ammunition in .380 ACP has come a long way with regard to terminal performance in recent years. Hornady's 90-grain .380 ACP Critical Defense load is a great example. (Photo by Muzzle Flash Media)

Historically, the .380 has struggled to consistently achieve that 12-inch penetration with standard loadings. You can “juice” the speed up a bit, but then you’re raising the pressure and most .380 guns on the market won’t tolerate the hotter loads. Certain brand-new offerings, such as Federal Punch have improved ballistic performance, but for most armed professionals and experienced trainers, .380 ACP remains the “hard deck” as far as defensive performance goes.

SIG Sauer P365-380 with optic, light and extra magazine.
The new P365-380 is fully capable, offering an optic-ready slide, accessory rail, and shipping with two magazines. (Photo by Muzzle Flash Media)

Once you embrace the .380 though, some of its advantages really appeal to certain shooters, foremost being its reduced recoil. It is much easier for someone with compromised hand strength to shoot 100 rounds of .380 in training than to do the same with 9mm. This isn’t an opinion, it’s a fact born out of working with numerous older and smaller shooters. The market has responded to this reality with several great offerings, such as the Smith & Wesson EZ. The ability to shoot more rounds more often is beneficial in the context of a holistic training plan and can not only impart necessary skill but also necessary confidence.

SIG Sauer P365-380 EDC.
Size and weight matters when it comes to EDC gear. The P365-380 is a great fit for a minimalist setup. (Photo by Muzzle Flash Media)

While not as large as some of the other .380 pistols on the market, the P365-380’s blend of ergonomics and size makes it an extremely easy-to-shoot pistol. I shot a 9mm model and the .380 side-by-side and noted that the latter had a much softer recoil impulse. Splits were fast and accurate, and even some less experienced shooters that I had with me were able to stack rounds on top of one another when shooting controlled pairs on paper and steel.

SIG Sauer P365-380 with Bushnell RXC-200.
For testing, a Bushnell RXC-200 red dot was mounted to the pistol's optic-ready slide. (Photo by Muzzle Flash Media)

For testing, I installed the excellent new Bushnell RXC-200 red-dot optic. It features a 6 MOA dot in a 15mm-tall window and installed easily. The combination of excellent optic along with the very shootable caliber made for a popular gun when I let the other shooters have a turn. When I started pushing the little pistol, I was able to get some impressive performance and split times, with the dot never moving out of the window. For a small gun, this can be a feat, but the P365-380 was up to the task.

SIG Sauer P365-380 magazine change.
The P365-380 ships with two 10-round magazines, one flush-fit unit and one with a grip-extending base pad. (Photo by Muzzle Flash Media)

At the 25-yard bench, the pistol held its own. It’s not a target pistol, but the dot and the 5-pound, 3-ounce, trigger helped me keep five-shot groups under 4 inches. Some groups came tantalizingly close to 3 inches, but this level of consistency and precision is reassuring in such a small overall package.

SIG Sauer P365-380 low recoil.
The ergonomic design of the P365 paired with the low recoil of .380 ACP makes it easy to get fast and accurate follow-on shots with the P365-380. (Photo by Muzzle Flash Media)

The P365-380 is not for everyone. If you shoot the 9mm version well, there’s no need for the ballistic downgrade. However, if you struggle with the current lineup of micro 9mm pistols, or you live in a country where “military” chamberings are not allowed in commercial firearms, then a P365-380 loaded with Federal Punch .380 ammunition might be just what you need.

SIG Sauer P365-380 testing.
After a little break in, the P365-380 proved to be as shootable and reliable with defensive ammunition as its 9mm stablemate. (Photo by Muzzle Flash Media)

SIG Sauer P365-380

  • Type: Striker fired, locked breech, short recoil operated, semi auto
  • Chambering: .380 ACP
  • Capacity: 10+1
  • Barrel: 3.1 inches
  • Overall length: 5.8 inches
  • Width: 1.0 inches
  • Height: 4.2 inches 
  • Weight: 16 ounces 
  • Finish: Nitron
  • Stocks: Polymer grip module
  • Sights: Optic Ready, SIG-lite night sights included
  • Trigger: 5-lb., 3-oz. pull (tested)
  • Price: $499
  • Manufacturer: SIG Sauer;


Federal Punch .380


  • Weight (Grains): 85 Grain
  • Velocity (FPS): 967 FPS
  • Standard Deviation: 18 FPS
  • Extreme Spread: 39.6 FPS
  • Average Group (Inches): 3.7 inches
  • Best Group (Inches): 3.2 inches

Federal Hydra-Shok Low Recoil

  • Weight (Grains): 90 Grain
  • Velocity (FPS): 943
  • Standard Deviation: 26 FPS
  • Extreme Spread: 57.2
  • Average Group (Inches): 3.6 inches
  • Best Group (Inches): 3.3 inches

Hornady Critical Defense

  • Weight (Grains): 90 Grain FTX
  • Velocity (FPS): 936
  • Standard Deviation: 14 FPS
  • Extreme Spread: 30.8 FPS
  • Average Group (Inches): 4.0 inches
  • Best Group (Inches): 3.6 inches
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