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Sig P365 Options & Upgrades

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The original Sig P365 SAS and an X-model FCU with and Icarus Precision Macro ploymer grip module and Maskas Precision 4.1" XXL Slide. Same gun, but very different.
The original Sig P365 SAS and an X-model FCU with and Icarus Precision Macro ploymer grip module and Maskas Precision 4.1" XXL Slide. Same gun, but very different.

This article is intended to serve as a reference for Sig P365 modifications and options including:

  • Slides

  • Recoil Assemblies

  • Triggers

  • Optics

  • Grip Modules


The Sig P365 was the first of the handguns now known as "micro compacts". These pistols are approximately the same size as the single-stack 9mms that had been all the rage just a few years earlier, but offered more capacity. Rapidly other gun manufacturers entered an arms race to produce their own take on the new form factor, but Sig took advantage of something that hadn't been commercialized before.

Legally the "firearm" in the US is the Fire Control Unit (FCU) of the Sig P365
Legally the "firearm" in the US is the Fire Control Unit (FCU) of the Sig P365

The Fire Control Unit (FCU) of the Sig P365 is legally the "firearm" in the United States. This means that owners of an FCU can change the grip module, slide, or any other parts without the hassle of aquiring another "firearm". While Sig was not the first to use a chassis system, they were the first to have it be considered the "firearm" and have become the king of supporting aftermarket support. FCU's can even be purchased separately ($359.99 direct from Sig) to allow you to build the 365 configuration of your own.

Sig currently offers 24 different models of P365 from 10-round original format up to 17-round "Macro" models, but that's just scratching the surface of what can be done with a P365 FCU. A few years ago I wrote a magazine article on some of the options available at that time. Now the P365 has grown even more and so it's time to look at some updates.

From Bottom to top: Original P365 SAS, Sig P365 XL, and Maskas Precision XXL Slides
From Bottom to top: Original P365 SAS, Sig P365 XL, and Maskas Precision XXL Slides

Slide Length is one of the most interesting to me. Part of what people love about the original 3.1" barreled 365 format was how small it is, however most ammunition is loaded to perform from a 4" barrel per SAAMI specifications. Sig and others do have specialty loads for shorter barrels (more on that Sig ammo HERE), but most over-the-counter ammunition needs more barrel length for optimal performance.

Additionally, longer slides make for longer sight radii, and usaually a slower, smoother recoil impulse. Sig offers the "XL" configuration which lengthens the barrel to 3.7", and now Maskas Precision offers an "XXL" slide which stretches things further for a 4.1" barrel (review on this set up coming soon).

Yes, going with a longer slide does make the gun larger, but the thinness that small-handed shooters and thinner-framed people looking for something easier to to conceal, remains.

If you'd like to try a factory Sig option those are available too direct from Sig for $329.99-649.99 you can turn slap an X-Macro Comp or Spectre slide on your basic P365 frame, just make sure you get the correct length recoil assembly.

Sig P365 XL top with standard recoil system. Maska Precision XXL slide bottom with DPM System recoil assembly.
Sig P365 XL top with standard recoil system. Maska Precision XXL slide bottom with DPM System recoil assembly.

Recoil Assemblies are also available to improve the shooting experience with a Sig P365. DPM Systems is a company that makes 3-spring systems for multiple firearms. As a fan, I've tried them in several handguns, ARs, and AKs. The DPM System assembly comes with three springs that are interchangable so you can tune the action based on your need, ammunition, and how well you grip the gun. I have tried the P365 solution ($95 from Optics Planet), but was not impressed with the results. The system for P365 XL models however, ($101 from Optics Planet) does make a significant difference. I have not had any ammunition sensitivities with it, even while running the strongest spring and low-energy ammunition.

Tyrant CNC Intellifire P365 Trigger
Tyrant CNC Intellifire P365 Trigger

Triggers are one frontier that as of yet seems to have little progress. Tyrant CNC has the Intellifire trigger (from $79.48 at Optics Planet) which did not have any appreciable effect on the trigger pull or travel on my FCU, but does add a physical safety; one aspect of the P365 that I know many people have been concerned about.

Two P365-appropriate optics, the Holosun 507K X2 (left) and Sig Romeo-X (right)
Two P365-appropriate optics, the Holosun 507K X2 (left) and Sig Romeo-X (right)

Optics: Optics-ready slides became available (from $299 direct from Sig) but a rolling change was made at some point between slides that retained the rear sight and slides that lost it. The benefit to slides that lose the rear sight is they seat the optic further back, lessening the amount of debris that collects on the front of the lens and reducing the chances of the optic causing a malfunction by deflecting spent brass back into the ejection port.

Some Sig P365 slides lose the rear sight but allow the optic to sit further back (foreground) while others retain the rear sight but push the optic forward (background)
Some Sig P365 slides lose the rear sight but allow the optic to sit further back (foreground) while others retain the rear sight but push the optic forward (background)

"Influencers" pushed and swore by the Holosun 507K X2 ($295.99 at Primary Arms ) and so many bought one, myself included. It's not a bad optic, but far from my favorite. The 2MOA dot makes sense for trying to slow-fire tight groups, but that's not what a "micro compact" pistol is for. We must use this small footprint optic because the slide is small. What part of that sounds like we also want a small aiming point?

Sig offered to let me try the Romeo-X ($399.99 direct from Sig) and at first I wondered if something 50% more expensive could really be 50% better, especially as a shooter that doesn't need a dot to perform. What I experienced and demonstrated in this video was that yes, sometimes it is worth paying more. Easier to adjust without needing a specialty tool, and although the Romeo-X also has a 2moa dot, the 32moa circle bring everything into perspective quickly and makes it easier to level on a target. The 2moa dot isn't simply floating aimlessly. Construction wise the battery compartment is much easier to access and the buttons give a positive click to let you know you've done something. The integrated fiber-optic rear sights line up perfectly with the factory front sight and aren't too bright to distract, but certainly make for quick reference.

Icarus Precision Sig P365 XL slide with Votatu PMD505-SG
Icarus Precision Sig P365 XL slide with Votatu PMD505-SG

A third option that just came in and I haven't shot yet is a more affordable option from Votatu in the form of the 505D-SG green dot. This appears to be somewhat a clone of the MeCanik M01 and was sent by Votatu. Feature set is nice with integrated irons, shake-awake, auto off, and physical buttons. The Votatu PMD505-SG is available from Amazon for $143.99 Fitment on the the Icarus Precision 365XL slide has a bit of overhang. I'll report back with more information as I gain it.

Sig P365 Grip modules from Sig, Icarus Precision, and Sharps Bros of various shapes and sizes.
Sig P365 Grip modules from Sig, Icarus Precision, and Sharps Bros of various shapes and sizes.

Grip Modules are one of the fun and easy ways to really try out something different. By simply punching out one pin you can remove your FCU and drop it into another grip; changing the way the gun fits your hand and even the capacity. Sig offers 24 different options for the P365 FCU ranging in price from $69.99 to $169.99 and keeping mostly with the standard design. With all grip modules be sure to check if the magazine release is included or not. I've been excited a few times only to learn I then had to order a magazine relesae kit seperately ($24.99 from Sig). They are easy to install with a few brave YouTubers risking a strike by showing how to install one.


If you want to try something of a unique design two that I've had good experience with are Sharps Bros and Icarus Precision. The Sharps Bros module offers interchangable grip pannels like a 1911, but my biggest love for it is the width. By widening the grip the gun feels more like a traditional compact. This sheds some of the "I got it because it's skinny" but also makes the gun a lot more comfortable on the range. Sharps Bros has also ensured that there are holsters for their modules ($275.45 at Optics Planet).

Icarus Precision is a big name in the Sig P365 and P320 world for grip modules, making their name by being one of the first to produce them from billet aluminum. Like the Sharps Bros module previously discussed, aluminum adds a little bit of weight, but drastically changes the feel. Aluminum can be matching more precisely than plastic can be molded and still have strength. This gives masterminds like Icarus Precision a wider range of possibilities even with the limited real estate a Sig P365 affords.

There are numerous Icarus Precision modules, some changing the dust cover length for a flush muzzle, others completely changing the way the gun feels in hand. Because they make so many models and also for the Sig P320, finding the one you want may take some time, but they are impressive ($249.99-449.99 at Primary Arms) Keep in mind that changing grip size may require the appropriate magazine, for example when going form a classic P365 to a P365 XL size. Fortunately the Sig store offers all the size blends from $49.99-59.99.

A box of Sig P365 Variety
A box of Sig P365 Variety

So what do you get after all of this tinkering? Isn't the total price equal to the price of another gun? Those are fair questions, and depending on what you're buying and which state you live in, how many firearms you want the government to know you own, it might be simpler to just buy another P365 than to build and alter, but I think that misses the point.

The point of all of this is to create the setup you want to run. We've proven time and again on the channel that as long as a firearm is reliable, most anyone can train to the point of being good with it. Some of these alterations may give you an edge by permitting a more natural proficiency through better ergonomics, easier sighting, lowering recoil, etc, but I think the real gain is making the gun yours. Aesthetics, ergonomics, and features are what you gain from all of this. Just as many of us enjoy personalizing a car, and certainly many enjoy personalizing a rifle, the brands and products listed above let you personalize you Sig P365 to the way you want it.


What have you built? Let us know in the comment section what you've tried and liked or what you want to try.

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Do any of these work on the 380 versions?

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As far as I know the only difference with the .380 models is the barrel and magazine. There may be other differences but I don't see them with my non-gunsmith eye. You might be able to change the grip module to another standard 365 size without issues.

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