The Sig Sauer P320 is a striker-fired handgun platform that was designed from the ground up to be customizable and modular. It was developed to compete in the MX17 Modular Handgun System trials, which it won.
After winning the competition the P320 received the designations M17 and M18 and was adopted by the United States Army, replacing the Beretta M9, which had been serving for decades. The P320 is now a favorite of law enforcement and self-defence enthusiasts as well.
The P320 is more than a handgun: it is a modern, modular firearm platform that can be customized to fit a wide variety of user’s needs, which means you can make a P320 totally your own.
In This Article:
Why upgrade the P320?
1. Make it yours
No matter the factory configuration of your P320, one thing is certain — it’s a great handgun. A base model will almost certainly take care of most, if not all, of your handgun needs. But, much like owning an AR, half the fun of owning a modular firearm platform is making it your own. Reconfiguring your stock P320 allows you to capitalize on so much of what makes the P320 great and dial in the areas that will make it even better for your intended purpose.
2. Adjust its size
With the modularity baked right into its DNA, the P320’s fit and function can be modded, tailored, and right-sized for you. From the size of the firearm, how you carry it, its performance, the scope of P320 mods available means every aspect can be tuned to fit a specific user’s needs. What’s even better — supporting customization was a central idea behind the design, so you tend not to lose any reliability as you tweak and customize your firearm.
3. Take it to the next level
At a minimum, we recommend picking up a few spare P320 magazines, but the sky is truly the limit. This high-performance platform comes ready to rock, and with just a handful of P320 upgrades, it can become a world-class handgun that works exactly the way you want it to.
P320 Grip Modules
One of the ways you can make the most dramatic change to a P320 is swapping out the grip module. In this case, the grip module holds the legally defined “firearm” components — the striker and trigger, which ride inside of the grip module. This means you can make significant changes to the firearm by swapping the grip module, all without any FFL paperwork.
This is great if you have the full-size model and want, for example, a smaller handgun for concealed carry, or simply want to use an olive grip with a black slide assembly.
Instead of buying a completely new gun you can simply reconfigure the P320 with your desired grip module. The best part? They’re remarkably inexpensive, often around $50.
There is a growing aftermarket for P320 grips, but the basics from Sig still ring true. The grip modules, changing in slide length, come in small, medium, and large. They also come in a version that supports the manual safety fire control module, which the military wanted for the M17.
We expect that a lot of folks will want to carry their P320 either concealed or as a duty weapon, and there are three examples of holsters that work well for these purposes.
For people considering a smaller grip module and thinking of appendix carry, a small Kydex holster like Concealment Express IWB holster, is an excellent option. Carried inside the waistband, you can, in fact, carry a full size 9mm without much, if any, printing.
For some additional comfort and a little more security on the belt, we recommend Crossbreed Supertuck holsters. They’re many people’s go-to for IWB carry as the patented design pairs a supple leather backing for flex and comfort with a form-fitted kydex holster specific to each handgun model. They make a ton of sense for appendix carry with the P320 as well as back carry if you’re standing for long periods and won’t be sitting much.
We also like their Quick Ship SuperTuck Bundle which pairs the Supertuck with a high-grade leather gun belt to give you everything you need and nothing you don’t. Not to mention Crossbreed has both a lifetime warranty and a no-questions-asked Try It Free, Two Week Guarantee to take the risk out of the deal.
For an outside the waistband holster, Raven Concealment Systems make great holsters that come with adjustable belt loops and offer good retention, which is vitally important when open carrying.
P320 Barrel Upgrades
Beyond the grip module, you can also swap out the barrels on the P320. Want to add a threaded barrel to run a suppressor? No problem. Look for something that will help improve accuracy? Done.
One note – the new barrel should match the length of your slide; full-size barrels go with the full-size slides and the compact barrels go with the compact slides — so verify before you buy. We’ve recommended two barrels here in particular, but this category goes deep, so do take your time to assess your options.
First, if you want to suppress your P320, the Silencerco barrels are the way to go. These barrels are high quality, stainless steel that will last for years. But the real trick here is the addition of threads so you can suppress your P320.
Since the P320 is certainly suited for competition use, a compensator is another upgrade. Compensators direct gas either up or to the side when a bullet leaves the barrel, making it easier to get back on target faster and reducing muzzle rise. There are a number of great options for the P320.
Assuming you’re running a threaded barrel, Tyrant Designs makes a line of quality screw-on compensators which also come in a variety of colors.
These little wonders not only vent gas to speed follow-on shots but add some weight up front. This added weight will further reduce muzzle rise, making these especially applicable for folks looking to build a competition gun.
If you’re looking for a paired compensator & barrel Griffin Armament offers a barrel that includes a mini-compensator and gives you the option of attaching a suppressor if desired. These mini compensators, while not as impactful as a dedicated comp, are great for carry enthusiasts as they will generally work with any number of holsters without modification.
Overall, an excellent option and you can even purchase the mini comp separately if you’ve already mounted a threaded barrel.
Another way to customize the feel of a P320 pistol is with an upgraded trigger. Swapping out the factory trigger for a flat opinion is quick and easy, and Sig offers one themselves in both a standard and skeletonized option which will help provide a more consistent trigger — especially for those with larger hands.
Far be it from us to knock curved triggers. If you’re not a fan of the factory trigger feel Apex Tactical has a nice curved option that claims a 35% reduction in pull weight thanks to geometry tweaks.
It’ll give you a lighter trigger pull for less than $50, if not exactly a life-altering upgrade from the stock trigger. Aftermarket P320 triggers are a simple, relatively inexpensive upgrade that can help you shoot more effectively.
A trigger swap for the P320 is fairly easy to pull off in just a few minutes with some basic tools and an online tutorial. If you’re looking for a more drastic change to trigger feel with a faster reset and shorter pull, Apex also makes an entire kit, including a flat trigger, trigger bar, and all of the pins and springs.
While it’s more involved than just the stand-alone trigger (and it will be more work) the snappier action and reset will have you pulling off rounds at a totally new clip. Plus who doesn’t love the feeling of gun parts on your bench?
Many people like Sig’s stock sights because they’re high-quality and easy to use plus their night sights are bright & usable as well. But, as with most things, they can’t be all things to all people.
- Black Sig sauer bright & tough night sight set with yellow rear/fits: Sig sauer models calibrated...
- 8 front sight and #8 rear sight
- Machined steel construction
If you’re going to suppress your P320, you’ll also want sights that lift your visual plane above the can. A good first step would be Trijicon’s excellent night sights for the P320. The front and rear sights are higher than stock, so you can see over a suppressor.
Beyond night sights, reflex and red dot sights have always been popular options for handguns, with Sig’s own Romeo Zero Reflex a solid go-to for many folks. It offers the Sig optical quality without the sting of higher end price points. Bear in mind that in order to mount an optic you’ll need a slide adapter plate, which enables you to mount a standard red dot on your P320.
- Spectra coat HD polymer lens with 10 times the impact resistance over traditional glass lenses
- Weapons grade ultra lite polymer housing, optimized for use with polymer pistols, concealed-carry...
- Stippling pattern on the housing matches p365 and p365xl grip pattern, for an integrated look
Lights & Lasers
While we’re on the subject of seeing what you shoot, a pistol light increases the utility of your handgun by giving you a way to identify targets independent of iron sights — which drastically improves usability in darker settings.
Since the P320 has 1913 rail on the bottom of the frame attaching a small weapon light, like the Streamlight TLR7 is quick and easy. It’s also a must have for anyone planning on using the P320 for home defense.
- 500-Lumens; 140 meter beam; Runs 1.5 hours
- Engineered optic produces a concentrated beam with optimum peripheral illumination
- Durable, anodized machined aluminum construction; IPX7; Waterproof to 1 meter for 30 minutes
If you don’t think a pistol light is such a bright idea (they can cramp your holster’s style quite a bit) consider adding a laser.
- BRIGHTNESS: Features a 5mW peak, 620-670nm, Class 3R visible red laser that is in conformance with...
- RUNTIME: 4 hours of battery life that runs on (1) 1/3N battery (included)
- EASE OF USE: Front activation button engages the laser immediately when the firearm is held in a...
Crimson Trace offers a Laserguard for the P320. These handy kits attach to the rail and give you an easy to operate laser sight that doesn’t add much bulk to the gun at all. The laser is operated by hand position alone, so there’s no need to fiddle with an on/off switch in the dark. It would also be a good idea for concealed carry use for these reasons.
PDW Kits & Braces
With the pistol brace craze in full swing, it’s no surprise that there’s a lot in interest in PDW kits for the P320. While none of them have been officially adopted by the military just yet, there’s this Exo One Exoskeleton is a drop-in PDW which adds a charging handle and M-LOK slots — plus the Exo One pairs with the Sig SB Tactical Pistol Brace for even more control (and frankly, it just looks badass).
Internal upgrades improve or speed the cycling function of the gun. In some cases that means higher accuracy, in other cases, it means skipping steps in the firing process to save time and effort.
- Cover Photo
- Wikimedia Commons, Streamlight on a Sig 226
- CNN, Jose Pagliery, Gun manufacturer waited months to warn the public its pistol could fire when dropped, June 6, 2018
- Wikipedia, SIG Sauer P320
- Military News, Matthew Cox and Hope Hodge Seck, Army Picks Sig Sauer’s P320 Handgun to Replace M9 Service Pistol
- Wikipedia, XM17 Modular Handgun System competition
- Salty Tactical, How to Change Sig P320 Grip Module, Nov 15, 2016
- Tactiholics, Sig Sauer P320 RX, Sep 2, 2017