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Sig P365 XL: 15+1 Gym Shorts Gun

If you didn’t know anything about the Sig Sauer P365 when it was released other than from a picture of it, you’d probably wonder why someone might grab one of these instead of a Smith & Wesson Shield or Glock 43. Until you saw the capacity. Hell, 10+1 was standard on the P365, almost double everything else in the category. Later down the line, Sig released magazine extensions, one even offering a 15+1 capability. Later they released the Red-Dot-Ready SIG P365 XL.

You have the same ammo capacity as the ubiquitous Glock 19, the universal standard to which all conceal carry pistols should be judged, in a substantially thinner and shorter pistol. But there’s more than a simple dimensional increase going on here.

SIG P365 XL magazines


The SIG P365 XL comes with many added features and improvements over its little sibling, the P365. First, an increased barrel and slide length gives the shooter noticeably reduced muzzle flip, a common issue with tiny 9mm pistols such as a Glock 43. However, the biggest positive with the increased overall length, at least for those with human-sized fingers, is that you can now really stretch out your support hand thumb on the slide without ending up in front of the muzzle. The ability to get a much more aggressive purchase on the gun allows for greater control and a major improvement in overall shootability and performance.


The next improvement is a flat-faced trigger, similar to those in Sig X series pistols. According to Sig, it breaks at 9 pounds and at 90 degrees; however, since we’re talking about a flat trigger, the weight varies from 3 pounds 8 ounces (bottom of the trigger) to 10 pounds (top of the trigger) depending on where your finger lays. Overall, though, it’s essentially a flat P365 trigger with no internal enhancements. While the flat face is a nice addition, especially since you tend to get more finger on the trigger on one of these little pistols, there’s no difference in the trigger’s feel. The SIG P365 XL trigger feels like a four-day-old carrot stick. Applying rearward pressure to the trigger, it provides a smooth sensation for about two-thirds of the way, then its mushy resistance up until the trigger break.

SIG P365 XL magwell

Another feature of the SIG P365 XL is a flared magazine well, giving the pistol a slightly wider mouth for inserting a magazine. While flared magwells are useful in more substantially sized guns, it doesn’t necessarily do much for this particular model. Anyone reloading this pistol with even moderately sized hands needs to be cautious during a magazine change to avoid getting pinched between the grip and magazine during insertion. The 15-round magazines are much easier to load, though this is more to do with their size than the magwell itself.

SIG P365 XL top

However, the SIG P365 XL also has a longer beavertail than the normal P365, and when used in conjunction with the magwell flare it can really help lock your hand in place. Provided your hands aren’t too large, the magwell aids in keeping your grip hugging the beavertail, ensuring a high hold without reaching the point where the slide will eat some skin. 

Where Sig really knocks it out of the park with the XL is by making it optic-ready. Yes, you read that right — a slim sub-compact, optic ready pistol with a 12+1 capacity. 

SIG P365 XL and SIG Romeo1

Don’t worry, if you’re still on the old-man-irons-only train and are still somehow interested in the SIG P365 XL despite the fact it’s neither a 1911 nor .45ACP, there’s no requirement that you use the plate. 


A new, pre-production, Sig Sauer RomeoZero red-dot optic installed on the pistol in about three minutes flat, using the tools provided with the optic. It was as simple as removing the slide, taking out the two internal screws that hold on a very well-designed cover plate/rear sight, and replacing it with the RomeoZero. 


Three minutes from start to finish — no machining, no fitting, no waiting around for weeks to get it back from a shop. It doesn’t matter if you’re still on the fence about optics; if you haven’t had the opportunity to try an optic on a pistol, you should.

Something to keep in mind about this review is that the RomeoZero we received along with the P365XL was a pre-production sample. There will be some in-line changes between our example and what you see on the shelf. We’ll point those out as we go along. 


The new, inexpensive all-polymer (including the lens) RomeoZero is very small indeed. It shares an optic footprint with the Shield RMSc, which means it fits nearly flush on the thin slide of the P365, and it’ll be much of the same story on other subcompacts such as the Glock 43. 

Because the RomeoZero has such a small profile, taller suppressor sights aren’t needed to cowitness, and there’s even a rudimentary, non-adjustable rear sight built right into the optic body itself. 

Like many popular pistol red-dots, the RomeoZero stores the battery between the optic body and the slide itself, which means the optic has to be removed in order to change the battery. Sig Sauer tells us the
RomeoZero has up to a 10-year battery life, so it’s not like this should
be a regular occurrence, however. 


The controls aren’t immediately intuitive upon first glance — one of the issues with receiving a prototype optic is that they generally don’t come with an instruction manual. There are eight brightness settings, selected by pressing a small button just behind the RomeoZero window. Once you hit the highest or lowest setting, the dot itself will blink several times to let you know. 

Smaller pistols are a challenge to shoot accurately, especially at longer distances. With the addition of an RDS, we mitigate that disadvantage. Twenty-five-yard alpha-zone shots were fairly easy to accomplish with a little bit of effort. And the challenge was mostly due to the size of the dot on the prototype Sig RomeoZero mini-RDS we were using. While the nominal dot size of the RomeoZero is either 3 MOA or 6 MOA depending on model, when our 6 MOA version was turned up to usable levels it became large enough to cover a 2-inch circle at five yards. At this level, head shots on a cardboard USPSA/IDPA were nearly impossible beyond 18 yards because the dot obscured too much of the target. 


Likely due to the nature of the plastic lens itself, there were also some odd reflections in the lens, which Sig assured us wouldn’t be present on the production models. 

As to how long an all-polymer optic will last? Plastic isn’t always a problem. Prior to later models of the series 1 Trijicon RMR, the optic that was proven to last the longest reciprocating on a pistol slide was the JPoint reflex sight — which was also all-polymer. While g-forces are hard on metal and glass, some polymers allow for more flex during operation, making for a longer-lasting dot. That said, we haven’t conducted any [totally unscientific] drop tests for durability.

SIG SAUER RomeoZero MRDS: $249


Tamara Keel probably put it best when she said the P365, “shot out spent brass like clowns exiting a car.” In other words, this pistol holds a helluva lot more ammo than one would expect. While the magazines do seem very small, they’re only slightly shorter than a Glock 19 magazine — though the grips of the two pistols are a different story entirely. 

SIG P365 magazine


When trying to shoot strong hand only, we ran into some issues; notably “Bang!” followed by a dead trigger. The slide was almost imperceptibly out of battery, and a gentle touch with the heel of the hand sent it the rest of the way home. If a death grip was applied, it functioned fine. This was an issue regardless of the ammunition we used. Note this is far from the only pocket gun we’ve seen with this issue.

To see if it was a fluke, Sig Sauer exchanged the first P365XL for another. XL number two came in with noticeably more lubricant and wear than XL number one, resulting in a smoother functioning gun. The lesson here is that if your pistol isn’t running one-handed, try lubricating it and wearing it in a little more. We don’t consider this a deal-breaker, just an FYI. There were no other malfunctions when firing one-handed, spanning the entire range of 9mm ammunition. 

SIG P365 XL and holsters

We did have one issue with the follower on the 15-round magazine getting stuck mid-magazine. The problem appeared where the 15-round magazine narrows into a single-stack for the last five rounds. The follower rotated and cammed into place during this transition. A quick tap-rack-bang got the stack moving again.

We contacted Sig about the issue, and they immediately offered to replace the magazine. We also heard from Phil Strader, Sig’s pistol line product manager, who said, “I’ve seen that happen a couple times, but only when loading or unloading by hand … never while firing.” Since the SIG P365 XL magazine body is the same part used in the standard P365 mag. (The only difference between the two is the floor plate.) 

The mag has proven reliable in the standard P365, so we think this was the product of an out-of-spec mag body more than a design flaw in the SIG P365 XL. 


This isn’t a custom-built, red-dot-equipped open class pistol made to ping steel at 100 yards. Could one make good hits at distance? Yes, but not as easily as with something with a more refined dot and a better trigger. 


The SIG P365 XL with an RDS is the ultimate gym gun. The size and weight makes 15+1 rounds absolutely disappear. Quality holster options are already on the market too. The PHLster classic 365 model works straight off the shelf, and the Dark Star Gear was able to get an optic compatible Hitchhiker and Koala mag carrier to work with no issues as well. Both options allow for easy, comfortable carry in a variety of attire. I even pulled off the P365XL in a pair of Lululemon gym shorts during a couple light weightlifting sessions.

Even with some warts, the pros outweigh the cons when it comes to the Sig Sauer P365XL, with the increased overall length representing the greatest improvement over the P365. The optic-ready capability really sets the gun apart and elevates the P365XL to a different level. It’s a great option for anyone who either already carries a dot gun, or is leaning toward one. 


Caliber: 9mm Luger
Weight Unloaded: 17 ounces
Magazine Capacity: 12 or 15 rounds
Overall Length: 6.6 inches
Barrel Length: 3.7 inches
MSRP: $579, ($828 with Romeo Zero)

[Editor's Note: This article first appeared in Concealment 15. Photos by Dave Merrill.]

More on Pistols, SIG SAUER, and 9mm Firearms


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