When the P365 first hit the market in 2018, it was the first of a new generation of wonder-nine, packing a full 10 rounds into a pint-sized package on par with the size of an average micro-compact. It quickly took the concealed carry market by storm, becoming the best-selling handgun in the US in 2018 and 2019 and arguably one of the best pistols for self-defense.
Fast forward to today, and nearly every concealed-carry handgun manufacturer has a double-stack micro-compact to rival the P365. Meanwhile, the P365 platform has expanded beyond just concealed carry, adding the P365XL and Macro variants.
Despite the glut of options in today’s market, the P365 platform remains one of the most popular and customizable options. Nearly every part of the pistol can be replaced, upgraded, or tuned, making the P365 a modder’s dream.
Why Modify the P365?
There are a lot of reasons to modify a pistol—softer recoil, faster target acquisition, a more secure grip, etc.—but the ultimate goal is really to make the gun better suit your needs and preferences. Often, that involves improving or adjusting more than just one attribute. Modders don’t want to improve just recoil or grip; they want to improve everything.
The P365 makes that process blessedly simple. Thanks to its self-contained fire control unit (FCU), every external component of the pistol can be replaced with minimal gunsmithing required. Gone are the days when you needed a Dremel and a soldering iron to change your grip’s texture; with the P365, you can just order a new grip online and install it at your kitchen table.
This means that once you’ve got your first P365 (or bare titanium-nitride FCU, which is now available from Sig Sauer and authorized retailers, for those who truly want a custom pistol from the ground up), you can turn it into anything you want. Your micro-compact SAS model can be converted into an X-Macro Tacops in a matter of minutes.
Beyond the convenience of the FCU, the P365 is exceptionally simple to work on, making it the perfect starting point for budding gunsmiths. It can be field-stripped without any tools and without pulling the trigger, and many of the small parts can be replaced with simple household tools.
Lastly, because of the P365’s popularity, aftermarket parts and upgrades are ubiquitous. Few pistols offer a more diverse and accessible aftermarket, and none of them do so with the convenience of an FCU.
An Overview of P365 Customization Options
P365 customization can be broken down into two main categories: OEM and aftermarket.
OEM parts offer guaranteed performance and greater inter-part compatibility but are limited in variety. These options include Sig’s Caliber X-Change kits, which allow users to completely change the size or caliber of their firearm, as well as standalone frames, slides, and small parts.
OEM parts offer the benefit of easy installation, predictable performance, and peace of mind. You never have to worry about them fitting properly or messing with your firearm’s reliability as long as they are installed per the instructions. You also won’t have nearly as much trouble finding a holster if you stick entirely to OEM parts.
However, OEM parts are not nearly as diverse as aftermarket ones. If, for instance, you like the size of your grip module, but would prefer if it were contoured differently, your only real option is an aftermarket model. While Sig offers grip modules in a variety of colors, finishes, and textures, they all share the same basic geometry within their size.
Aftermarket parts, on the other hand, offer a much greater range of options. Continuing with grip modules as an example, aftermarket options include not only a variety of textures and colors but also materials and contours. Some include replaceable grip panels or thumb ramps, while others may integrate undercut trigger guards or magwells.
This same variety is available for nearly every major part of the P365.
In fact, for some parts, aftermarket may be the only option for upgrades. Recoil springs and guide rods, for example, have several aftermarket options for different designs and weights, while the OEM catalog is limited to one.
However, aftermarket parts also come in a range of quality. Some may fit better than others, and some may even require a bit of custom fitting with a file for proper installation. Custom parts are also frequently made to different specifications than OEM parts, and so while most are tested to be functional in a stock P365, combining multiple aftermarket upgrades can create compatibility issues.
Additionally, larger aftermarket parts such as slides or grip modules may make it difficult to find the best holster for you, as most commonly available P365 holsters will be made to OEM dimensions.
Best P365 Upgrades and Parts
With the field of P365 parts and upgrades being so vast, we can’t review every option out there—or even just every good one. But, below we’ll take a look at some of our favorite choices from each category.
Before we do, though, it’s worth noting that if you use your pistol for concealed carry or personal defense, we recommend some careful consideration before deciding to modify it.
The legal ramifications of modifying a defensive pistol are hotly debated, and not something that we’ll bother rehashing here, but suffice to say that the wisdom of doing so is subject to some controversy, and ought to be considered.
Moreover, even high-quality upgrades can have a detrimental effect on reliability, particularly those geared more towards competitive use than defensive. We heavily recommend thorough testing of any aftermarket part before relying on it for personal defense.
Best Grip Modules
One of the biggest advantages of having a self-contained FCU is the ease of switching groups. With many firearms, the grip itself is serialized and regulated, but in the case of the P365, it’s entirely unrestricted.
OEM P365 grip modules offer a range of sizes, with the recently released Macro grip being the largest. The Macro was a game-changer for the P365, offering a full-sized, albeit still slim and concealable, grip that could accept a 17-round magazine. This puts the P365 on par with most full-size pistols for capacity.
The Macro grip also offers changeable backstraps, letting users customize the way the grip fits with their hand, and an optional magwell for faster, easier reloads, making it our favorite of the OEM options.
If you’re looking for a more radical change to your pistol’s feel, the aftermarket has you covered. With grips available from Icarus Precision, Sharps Bros, Wilson Combat, Mischief Machine, and more, there’s no shortage of options.
The Sharps Bros P365XL grip module is one of our favorites, drastically changing the firearm’s aesthetic and feel. It’s roughly the same size as a P365X or XL grip and accepts the same 12-round magazines, but is machined entirely from 7075-T6 aluminum.
This style of construction makes it much more rigid than polymer. The Sharps Bros frame also integrates a double undercut in the trigger guard, allowing users to grip higher on the pistol for greater control. The thumb ledges machined into the frame also help users put more downforce on the pistol to fight recoil.
Arguably the most radical difference, though, is the cherrywood grip panels, which give the frame a timeless classic aesthetic reminiscent of the 1911. The panels also slightly increase the girth of the grip—a godsend to those of us who found the width of the OEM module a little lacking.
Sadly, though, at the time of this writing, the Sharps Bros grip is available in only one single size. For compact or full-size options, we recommend the excellent grips available from Icarus Precision.
Icarus Precision is one of the earliest companies to start producing all-metal machined frames for the P365 series. They now offer an entire line of P365 grips in a variety of sizes, including both compact and Macro-equivalent grip lengths.
Their flagship is arguably the ACE 365 EVO grip module, which offers a plethora of features to increase shootability at the cost of a modicum of concealability.
It starts with the extended, upswept beavertail, which helps users situate their hand as high as possible while still protecting them from slide bite. The swelled backstrap also does an excellent job of forcing the hand into a high, consistent position time after time, eliminating the tendency some users have to adjust their grip after drawing from the holster.
Combined with the aggressive double-undercut trigger guard, this whole frame works in concert to position your hands in the exact proper position with minimal conscious effort. The frame further integrates ambidextrous thumb ledges, similar to the Sharps Bros frame.
A partially-flared magwell, which opens up at the rear and on the sides of the grip but not at the front, makes reloads incredibly forgiving and lightning quick but doesn’t inhibit the user from slamming home flush-fitting 12-round magazines either. It’s a tricky balance to strike—too much flare and users will have to use extended magazines or baseplates to be able to seat their mags, while too little won’t have the desired benefit—but Icarus Precision has found a clever solution with their ACE 365 Pro frame.
Last, but hardly least, the ACE 365 Pro frame does away with Sig’s proprietary accessory rail in favor of a section of standard Picatinny, significantly increasing user’s available options for weapon lights and lasers.
Sadly, both the Icarus Precision and Sharps Bros frames alter the P365’s geometry enough to require a custom holster; common off-the-rack options aren’t compatible.
Best Slide Upgrades
When it comes to slides, modders have a veritable smorgasbord of options, both OEM and aftermarket.
Because of the P365’s modular nature, any P365 slide can function with nearly any P365 frame. This means that users can select the length that best fits their use case from among the OEM slides, even if they want to make a configuration that isn’t typically available from the factory, such as an XL slide on a standard P365 grip.
OEM options go beyond just length, though. Sig Sauer also offers Spectre variants of most slides that feature additional slide cuts and serrations for a more aggressive look, as well as Comp versions that integrate a compensator into the front of the slide, although these may require an adjustment to your barrel length as well.
Aftermarket options offer a similar variety; there are models available in every length from makers such as Strike Industries, Grey Ghost Precision, Zev Technologies, True Precision, Norsso, and more. Many of these slides offer custom porting, increased serrations, lightened overall weights, or proprietary optic cuts.
Of the many excellent options, we’re fond of the Strike Industries Strike Slide. It’s a no-nonsense slide that’s packed with features but light on unnecessary frills.
Like many OEM slides, it offers front and rear serrations, but it also integrates several additional slide cuts for reduced weight. This weight reduction is small enough that it doesn’t make a huge difference when carrying the pistol, but can slightly mitigate felt recoil and increase cyclical speed, especially when combined with a reduced-weight recoil spring.
The slide is milled for the direct attachment of any optic with an RMSc footprint, making it easy to find a compatible optic, although you will need an adapter plate for certain optics, such as the Trijicon RMRcc.
Uniquely, the Strike slide comes with optional charging wings that can be installed on the rear of the slide, which makes it easier for users to charge the firearm, particularly those with weaker grip strength or with an optic installed.
Best Barrel Upgrades
P365 barrels are one of the few parts in which there is not all that much variety to be had. You can have your choice of threaded or unthreaded, and in a variety of colors, but that’s essentially it—there’s only so much modifying you can do to such a simple and crucial part of the gun.
OEM options are limited primarily to different lengths, as Sig does not currently offer threaded barrels. They do, however, offer a ported option for those looking for recoil reduction, but it will require the use of a corresponding ported slide.
Aftermarket options are available from True Precision, Faxon, Strike Industries, Griffin Armament, and more. Many of these are available in standard colors, like black, as well as more ostentatious options like gold, bronze, or even multi-color patterns such as Faxon’s Chameleon PVD finish.
Several aftermarket barrels offer various types of fluting, which can slightly reduce weight, increase heat dispersion, and reduce friction.
True Precision‘s threaded barrels are an excellent example of an aftermarket option designed for function over form, although we can’t say they don’t look great, either.
These barrels offer drop-in installation and incredible attention to detail in both the machining and the finish. Each barrel comes with a thread protector and O-ring to insulate your threads against damage when you don’t have a muzzle device installed.
Best Muzzle Devices
If you want a muzzle device for your P365, you’ll have to look to the aftermarket; Sig doesn’t offer any OEM muzzle devices, although their Spectre Comp slides do offer much of the same functionality.
Aftermarket brakes and compensators are available from Tyrant Designs, Parker Mountain Machine, Griffin Armament, Strike Industries, and others. Technically, you could install nearly any muzzle device with an appropriate thread pitch onto a P365, but the models available from the aforementioned companies are small enough not to get in the way, even on such a compact pistol.
Compensators offer recoil reduction ranging from slight to significant, often depending on the size and weight of the comp. This is a sizeable advantage to both speed and precision, so it’s no wonder that they are the most common option for handgun muzzle devices.
There are many excellent compensators available, but some of our favorites are the Griffin Armament Micro Carry Comp and the Tyrant Designs P365 Compensator.
The Tyrant Designs compensator is made specifically for the P365. It can attach to any 1/2-28 threaded barrel and doesn’t require any shims or set screws, making it exceptionally easy to install, and easier than most to remove for cleaning.
Because it is sized specifically for the P365, it’s compatible with most open-ended holsters, although the added length may be a concern for those who carry their P365 concealed.
The Griffin Micro Carry Comp, on the other hand, is quite small and adds negligible length over a threaded barrel. It can fit with most open-ended holsters and even some that are not open-ended but are designed for use with threaded barrels.
However, owing to its minuscule size, it does not offer quite as much recoil reduction as larger compensators.
Best Trigger Upgrades
Unlike some of its competitors, the P365 comes with a very acceptabletrigger right out of the box—but not everyone is satisfied with just acceptable
The easiest way to improve the pull is to drop in an OEM P365 flat trigger shoe; the improved geometry repositions the user’s finger lower on the trigger, maximizing mechanical advantage. This doesn’t do anything to reduce the weight of the trigger, but because of that mechanical advantage, it will often feel slightly lighter.
Many users also find flat triggers to offer a more predictable break, allowing for more precise fire. This flat trigger has the advantage of being an OEM part, meaning you won’t have to worry about compatibility or reliability.
Several aftermarket trigger shoes are also available, both in straight and curved profiles. Many of these offer additional features such as reduced weight or tuneable overtravel—at a suitably enhanced price, of course.
Best Magazine Upgrades
Sig now offers P365 magazines in a variety of sizes and capacities, ranging from 10 to 17 rounds. The compatibility of your P365 with OEM magazines will depend on the size of your grip; P365 grip modules can accept magazines larger than their flush-fit size, but not smaller. For example, a P365XL, which has a flush-fitting 12-round magazine, could accept 15 or 17-round magazines, but not 10-round, except for certain larger 10-round magazines intended for restrictive states.
If you need more capacity, though, aftermarket extended baseplates are available from a number of manufacturers.
Additionally, some manufacturers, such as Icarus Precision, produce aftermarket baseplates machined from aluminum to increase the empty weight of the magazine, ensuring it will drop free quickly when the magazine release is depressed, which can speed up reloads under adverse conditions.
Best Sights and Optics
While optics are really more like P365 accessories rather than parts, they are still one of the most common upgrades people make to their pistols. With the exception of the base P365 and the SAS, nearly all P365 models are now optic-ready from the factory, so there is little reason not to add a mini reflex sight.
Options from Sig Sauer, Trijicon, Shield Sights, Holosun, and our own Primary Arms Optics are all popular.
Sig Sauer’s own ROMEOZero Elite is the only one that is available preinstalled from the factory, providing a perfect option for those who want the speed and capability of a red dot but prefer not to tinker with their firearm themselves.
Our own Primary Arms Classic Series Micro Reflex Sight will also fit the P365 optic cut without an adaptor plate and offers an affordable option for those who desire a red dot that won’t break the bank. As you’ve come to expect from Primary Arms optics, it punches well above its weight class with a battery life of up to 40,000 hours.
Lastly, the Holosun 507k will also fit the P365 without an adaptor. While pricier than the Classic Micro Reflex Sight, the 507k offers built-in rear iron sights and Shake Awake technology. It’s also available with the excellent ACSS ® Vulcan ® Dot reticle.
The Vulcan Dot reticle augments the standard dot aiming point with a massive 250 MOA circle. During normal aiming, this circle is located outside the user’s field of view, but when the firearm is misaligned, it becomes visible, indicating to the user how the firearm is misaligned. This allows the operator to make rapid corrections and get back on target faster, ameliorating one of the key drawbacks of pistol reflex sights.
If all these options seem dizzying, check out our Red Dot Buyer’s Guide for a more thorough look at choosing the best red dot for your applications.
For those who still prefer iron sights, there are still plenty of options around. Most P365 models come straight from the factory with tritium iron sights, but fiber optic, blacked out and traditional three-dot P365 sights are available as well from numerous manufacturers.
Some users opt to both upgrade their P365 iron sights and add a red dot, utilizing suppressor-height sights to achieve a cowitness. This allows users the performance of a red dot while still having the peace of mind of irons.
Best Lights and Lasers
Which pistol lights and lasers are available for your P365 will depend primarily on which grip module you have installed.
With an OEM grip module (or an aftermarket module that utilizes an OEM rail profile), you’ll be able to choose from options from Surefire, Streamlight, Sig Sauer, and others.
Sig Sauer offers their Foxtrot series of lights and Lima lasers for the P365. All of these options mount securely to the OEM rail and are activated via a pressure pad that sits against the grip, allowing them to be actuated by merely squeezing your middle finger around the gun.
This method of activation makes them very instinctual and easy to use, particularly for those who are not trained in the use of a weapon light. However, they do tend to activate whenever the firearm is gripped firmly, such as when drawing or firing. This can be either a benefit or a drawback, depending on your intended use.
Offerings from Surefire and Streamlight utilize a more traditional switch system, allowing users to control the light with their offhand thumb without breaking their grip. Surefire’s XSC and Streamlight’s TLR-7 Sub are both available in versions that fit the P365’s standard rail.
Surefire’s XSC utilizes a rechargeable battery pack, eliminating the need to buy replacement batteries again and again, and outputs a respectable 350 lumens.
Streamlight’s popular TLR-7 Sub P365 light is fueled by standard CR123 batteries and manages 500 lumens.
For those utilizing aftermarket frames, such as the Icarus Precision ACE Pro, or X-Macro frames, light and laser options abound. The standard Picatinny rail can accept most compact weaponlights and lasers, including popular models like Streamlight’s TLR-7a and TLR-8 models, and even full-size options like the TLR-1 HL.
As with red dots, we have a handy guide on choosing the best pistol light for concealed carry for those looking for more information.
No matter how you want to customize your P365, there is a part for you. From ultra-compact 10-round carry guns to full-size IDPA competition firearms packing 17 rounds (or more), the P365 offers an insanely diverse range of capabilities, all with a single FCU.