The origins of the SIG-Sauer company lie in the company named Schweizerische Waggon Fabrik or Swiss Wagon Factory (in English) which was founded in 1853 by Friedrich Peyer im Hof, Heinrich Moser and Johann Conrad Neher.[1][2] In 1860, a state-of-the-art rifle of their creation won a competition by Switzerland’s Federal Ministry of Defense, resulting in the award of a contract to produce 30,000 Prelaz-Burnand rifles. The Prélaz-Burnand 1859 was invented by gunsmith Jean-Louis Joseph Prélaz and an army officer Edouard Burnand and adopted as rifle M1863 (15,566 made by SIG)

Unlike any other pistol in its class, the SIG Sauer P320 Pistols feature a unique modular-grip frame and removable fire-control assembly that allow you to change calibers, sizes and fit for a truly custom experience. A three-point takedown safety system will not allow you to break down the firearm with the magazine in the gun or without the slide locked to the rear, making it difficult for an accidental discharge to occur. Interchangeable polymer grips offer a secure hold and accommodate a wide range of hand sizes. SIGLITE® night sights provide target acquisition in any lighting situation. Lightweight and durable black polymer frame and Nitron® slide. Double-action striker fire operating system. Quick takedown with no tools required.

When I look at a new gun, I like to spot the one big thing that’s different. I hope there is something noteworthy and unique, or else it would be like plenty of other guns, and that would be a boring review, wouldn’t it? With the Sig Sauer P320, finding that one big area of differentiation was easy: its modularity. Well, technically speaking, I suppose there are three big areas because that modularity concept applies to fit, size, and caliber.


Most handguns come with optional grip back strap pieces of different size. The idea is that, with one of these inserts, you make the grip larger because adding a larger back panel makes the back bigger. But that’s exactly what the back strap approach does – make the back strap bigger. It’s not a holistic approach to grip size. If you want to fit a P320 to a shooter with smaller or larger hands, you replace the whole lower frame. Sig offers small, medium and large grip size frames to fit a wide variety of hand sizes. That sounds complicated and expensive, but it’s not, as we’ll see in a minute.


If you use a gun, it can be awfully handy to have different sizes for different purposes. If you choose to carry one concealed, something more compact is a plus, because it’s easier to hide and lighter to lug around. If it’s for home defense, something physically bigger can be a benefit as a larger and longer gun is easier to aim and control and it holds more cartridges. If you like to compete in shooting sports, a larger gun with more capacity is also desirable.

What would be really cool is having the same exact gun fit all these needs. If it had the same trigger and feel of operation, the same mode of operation and the same overall feel, you’d be a better all-around shooter because you’re always using the same basic gun. That’s exactly what Sig did with the P320 platform. Besides the frame, the ability to swap out the barrel and slide is also part of the deal. The best part is that you can do all that without more background checks and paperwork with your dealer. You can even order the components online. Sig P320 components will be available to configure full-size, compact, and subcompact sizes. Hold this thought too – we’ll explain in a bit.


If you’re going to figure out how to make the same gun fit different shooters and come in completely different sizes, why not allow the owner to change calibers too? Certainly military and law enforcement users may have a desire to use different calibers for different purposes, but us regular folks might want to do that too. What if you could, using the same serialized gun, shoot lower-cost 9mm loads to practice or compete on weekends, but change to something bigger like .357 Sig, .40 S&W, or even .45 ACP when you want to use the gun for defensive purposes? Well, the P320 will let you do that too. Next, we’ll explain how


A Different Approach to Modularity

Most handguns are legally defined by the frame itself, which contains the trigger, hammer, striker, or whatever other components make the gun go bang. Since the part with the serial number comprises most of the gun, it’s not really feasible to swap major components.

The P320 takes an entirely different approach. Sig designed the pistol so that the “legal gun” is just a single modular system that contains the trigger and striker system. You drop that into the frame of your choice, and stick the barrel and slide of your choice on top. The modular “gun” assembly doesn’t know or care what caliber you’re shooting, so that’s how you can even change your “gun” to a completely different caliber.

It’s a great idea, especially since the most important parts to keep identical across various gun configurations are the trigger, striker, and operating controls. If you buy a Sig P320 and accessory parts to turn it into different handgun configurations, you won’t be shooting similar guns or guns that feel like your other ones. You’ll actually be shooting the exact same gun.


When it comes time to take apart the 320 for cleaning or changing out some of the modular parts, you can do it without pressing the trigger. Some guns require a trigger press to release the striker tension before you can remove the slide, recoil spring, and barrel. With the Sig Sauer P320, all you have to do is pull the slide back, lock it in place with the slide stop lever, remove the magazine, and rotate the takedown lever. The pistol is designed not to come apart unless the magazine is out and slide locked back. Now the slide, barrel and spring will slip right off the front of the frame. No trigger manipulation is required.

At the Range

The Sig Sauer P320 has a grip angle more like that of a 1911 pistol – closer to vertical. It’s not so severely angled as a Glock. I mention that because different shooters have different grip angle preferences. For me, the P320 points very naturally. If I close my eyes and raise the gun, it’ll be on target, with no need for alignment.

The gun I tested was chambered in .357 Sig. If you haven’t shot that before, it’s somewhat aggressive. While the construction and case dimensions are slightly different, it’s like a .40 S&W cartridge case necked down to accept a 9mm bullet so it looks a little bit like a stubby rifle cartridge. The whole point of it is that the extra case capacity drives the bullet a couple of hundred feet faster than a 9mm. It’s not uncommon for a .357 Sig bullet to exceed 1,400 feet per second. I mention all this to make the point that the round has snappy recoil, but I found the P320 easy to shoot, even with the sharp recoil. The grip on the P320 is far more rounded than that of a Glock, so I think there’s better contact with the hand, making the gun more controllable under heavy recoil.

I did some fairly geeky accuracy testing in an informal head-to-head test against a brand new Sig Sauer P226 chambered in the exact same .357 Sig chambering. To take my aging eyesight out of the equation, because that would almost certainly foul up the results, I mounted a Bushnell Elite 3500 Handgun Scope on each gun using a UM Tactical rail-mounting adapter. The Bushnell offers variable 2-7x magnification, so I was able to get a perfect sight picture of my targets 25 yards down range.

I fired multiple five-shot groups for each type of ammo and averaged the results. I figured this approach was at least half-scientific and would give me a decent representation of which gun was technically more accurate. Guess what? The modern plastic modular P320 beat the old steel P226 warhorse.

MSRP for the P320 ranges from $628 to $713