Overview
But first, let’s do a little overview. The SIG P365 is a 9mm striker-fired, semi-automatic pistol. It is one of the most popular carry guns ever. When introduced in 2018, it was the highest capacity firearm for its size and weight. The heart of that is really the magazine, as SIG used a unique double-stack configuration that was able to cram 10 rounds into a tiny package.
Related Review: Why I (Still) Think the SIG Sauer P365X is a Perfect Carry Gun
In addition to size and capacity, SIG also designed a relatively soft-shooting, accurate, and reliable firearm. There were a few problems early on, but they have since been overcome.
The other key feature of the P365 is the independent fire control unit. The internal module that houses the trigger and firing mechanism is the serialized part of this gun – it’s what must be registered as a firearm. Because the fire control unit is modular, it can be put into different size frames and use various lengths of slides and barrels.
This, combined with the size, is the real magic of the 365. SIG (and the ingenious aftermarket) has evolved the P365 platform into one of the most versatile pistol systems in the world.
Related: SIG Sauer Factory Tour – Birthplace of the P365, P320, MCX & More
My Journey
So, what can you do with this gun? I’m going to walk through my journey with the P365 XL to illustrate the options.
I initially purchased the P365 XL with a SIG Romeo Zero installed because I wanted a red dot gun that was small enough to conceal but large enough to have a full firing grip. The XL has a slightly longer barrel, slide, and grip than the original 365. It also holds two more rounds than the original 365.
The XL worked well in this capacity. The size was pretty much perfect to conceal in the appendix position. I’ve also been playing around with a multi-fit Falco holster, which is super comfortable and great for driving or when I’m going to be seated for long periods of time.
This SIG is just a great all-around pistol. It has good, simple controls, and reliable, comfortable ergonomics, and it's relatively soft shooting. But that didn’t stop me from tweaking it to see how far I could take it.
My modifications basically fall into four categories: sighting systems, cosmetics, grip, and performance.
Sighting Systems
The first and most obvious modification available is to change the sighting system. The Romeo Zero initially worked and was a great size for carrying, but I dropped the gun once and it lost zero. This made me lose confidence in it, so I replaced it with a Holosun 507K, which has given me no problems.
Both SIG and aftermarket companies have tons of options for iron sights and red dot optics. The SIG SAS slide has a Meprolight MePro FT Bullseye Rear built into the slide so you get a completely snag-free sight, which I think is really neat since I’ve been playing with pocket carry lately.
Bling
My second modification was just about looking cool. Since I carried it often, I wanted to "bling" it out a little bit. This is now super easy and relatively affordable for modular guns. You no longer have to send your gun off to a custom shop to get it coated and upgraded. No more risk of losing your firearm in the mail. No more being without your firearm for weeks or months while the work is done.
Now you can have frames, slides, and barrels sent directly to you. Companies have ready-made designs, or you can get something custom. But because it’s basically plug-and-play parts now, you can mix and match whatever you want. SIG also sells basic replacement grip modules starting around $60, so you can order one yourself and experiment without risking damage to your pistol.
My first custom grip was a Fdez Werx black and gold camo XL frame and a True Precision gold barrel that is threaded. I thought it just looked cool. I even got the matching extended magazines.
Grip Mods
Moving on to grip modifications. SIG makes three basic sizes of grip modules, and they are characterized by the number of rounds that can fit into the gun with a flush-fitting magazine. The original held 10 rounds; the XL size increased it to 12 rounds; and the XMacro can fit 17 rounds.
With these three sizes, you can mix and match to whatever capacity works best for your particular situation. But size isn’t everything. Shape is also important.
My biggest gripe was that I was not able to get a consistent grip when drawing. It wasn’t the size of the grip, because that was large enough for me to get all my fingers around it. It was the shape, because my Glock 19 has a similar length grip, but I could more consistently draw. The P365 grip shape didn’t give my hand enough index points to key off of, which also affects recoil control.
My solution was to get another XL grip modified by Boresight Solutions. Their Razorback mod adds a hump to the backstrap, which allows the gun to fill out the hand more fully. This assists with recoil control and getting a drawing grip. For me, it was a game changer.
Now, many companies have added all kinds of refinements to all sizes of P365s. There are metal grips and grips with standard Picatinny rails. (The 365 has a SIG proprietary rail.) There are frame modules that change the grip angle and dimensions to fit different hands. There are even companies that do grip shapes similar to the Razorback. There is something for everyone.
Barrel Performance
My final modification category is barrel performance. There is so much you can do to the slide and barrel to reduce recoil and muzzle rise.
A few current SIG models (such as the XMacro Comp) come with compensators. SIG does its compensators a little differently, though. Traditionally, ports are cut into the barrel to redirect the gas, or a compensator is installed to the end of the barrel to do the same thing.
Related Review: 17+1 Optics Ready SIG P365 XMACRO Comp
SIG doesn’t modify its barrels; instead, SIG takes the longer slide such as the XL slide and installs a shorter barrel as on a standard 365. With the extra slide length, ports are cut into the slide. The extra slide length becomes the compensator expansion chamber.
SIG sells these slides as standalone parts, or you can buy aftermarket slides that do the same thing. But the aftermarket also offers standard porting and compensators that screw on to threaded barrels.
On my XL, I added a Griffin Armament Micro Carry Comp on the True Precision threaded barrel. I didn’t want something big, since this is my carry gun. I just wanted a little added assistance. Regardless of what type and size of recoil compensation you want, there is probably something out there that fits the bill.
Conclusion
Today, with the 365, you can basically build anything you want. I also got an original size P365 grip so I could pocket carry this gun. I remove the optic when I want to pocket it. I’m also thinking about getting an aftermarket XMacro-sized all-steel frame so I can compete with my SIG.
