When you think of Sig Sauer pistols, you think of classic double/single-action. Or single action like the new P938 and classic 1911s. Or maybe that Double Action Kellerman (DAK) design. What you don’t think of is striker-fired.
While the new P320 clearly inherits some ideas and inspiration from the modular Sig P250 design, the action is all new. It’s a constant action, striker-fired pistol, complete with the internal safeties you would expect in a striker design.
Being a .357 Sig caliber nut, I just had to try one out in that caliber.
In the box
This Sig Sauer P320 chambered in .357 Sig came with two (14) round magazines. Additionally, Sig includes an outside-the-waistband Kydex paddle holster. The holster is marked “P250 Full Size” and “P250 Compact” which implies holster compatibility across those models. The holster includes a retention screw to adjust the tension to your preference. The lockable hard case also includes owner’s manual, a cable-style gun lock and a small tube of Sig Sauer Mil-Comm TW25B lubricant and protectant.
A quick and dirty tour
The slide release lever is not exactly ambidextrous, there are actually two of them already in place, one on either side.
The magazine release button is, in fact, ambidextrous. By default, it’s on the left side of the pistol. It’s easy to reverse to the other side, again without specific tools. A paper clip is all you really need to release it from the grip model and reinstall on the opposite side.
The sights are SigLite with tritium inserts and they’re made of steel so you can rack this gun on a belt, boot or hard surface without worry should the need arise.
Following the steel parts theme, the magazines are also made of steel. They drop freely when released, but seat with equal ease. No encouragement is required to lock them in place. The guide rod is also made of steel.
The first thing I do with a new pistol is press the trigger – a lot. I worked this one quite a bit and found it to be – awesome. For a striker-fired pistol, it’s smooth and crisp. A brief take up is followed by short travel of constant pressure and a clean break. The reset is positive and very easy to feel if you’re into that sort of thing. I measured the press weight at six pounds, although it felt lighter.
As a classic striker-fired gun, there are no manually operated external safeties. However, that doesn’t mean there aren’t internal safety systems in place to help prevent unintended discharges.
An internal striker safety locks the striker in the back position until the trigger is pressed all the way to the rear.
A disconnect safety prevents the P320 from firing when the slide is out of battery. With everything unloaded and the magazine removed, I tested this out by pulling the slide back a fraction of an inch then pulling the trigger. Sure enough, the striker didn’t release.
A three-point take down safety design ensures that the takedown process won’t work until the slide is locked to the rear, the magazine is released, and the slide can be removed without need of pressing the trigger.
The standard P320 does not need a tabbed trigger insert to provide drop safety. However, if you want that, it’s available as an option. The P320 also, by default, will fire without a magazine in place. If you prefer the opposite scenario, you can order the P320 with a magazine safety. I think it’s interesting how the Sig folks have taken full advantage of the modular design and side-stepped those issues that upset people so much. Like a magazine safety? Great, buy it that way. Hate that? Great, buy it that way. It’s hard to go wrong when you give customers what they want.
It’s a gun, but not exactly…
When you look at what most would consider the “frame” of the Sig P320, you’ll see all the normal stuff: grip, trigger guard, mil-spec M1913 rail up front and a cutout on the right side that shows the serial number. But wait! That’s not actually a frame, it’s just a part. You can buy one wherever you like and without a background check. You can even order one online and have it shipped to your house.
Sig calls the firing system the frame. Think of the “frame” as the firing control system – trigger and internal safeties. The striker itself resides in the slide assembly. The frame also includes four stainless steel slide rail guides, two on each side, front and back. In addition to being able to change grip modules, you can also change caliber by adding the appropriate slide and barrel to the frame. Right now, the P320 is available in 9mm, .357 Sig, and .40 S&W. Soon, there will be a .45 ACP option too.
While that sounds nifty for shopping convenience, there’s a good reason that the “frame” is not really the frame. The collection of mechanical stuff that’s defined as the serialized gun is contained entirely inside of the frame, and you can take it out without the aid of hammers and such. The idea behind this modular design is that users (individuals or perhaps military and law enforcement agencies) can configure each pistol to different specifications. My test P320 came with a “Full Medium” grip module. That means the grip circumference is the medium size, but the “frame” (read grip module) is full-length and full height. If I want, I can order a smaller grip module and slide assembly that will convert my P320 to a compact carry gun. Instead of the replaceable backstop approach used by many gun makers, Sig offers entire grip modules in small, medium and large circumference sizes. No parts to move around – it’s a solid configuration as the entire grip module (frame) is a single piece.
I’m thinking that small, medium and large grip sizes don’t mean much to you without some point of reference, so let’s try to provide that. The one I have here has a medium grip size. Measuring the circumference with a tape, I come up with about 5 5/8 inches at the widest spot. That’s almost exactly the same as the grip circumference on my FNS-40 with standard back panel, Beretta Px4 with medium grip panel, and Glock 31 Gen 4 with no back panels installed.
Frames also come in different overall sizes (not just grip circumference) and right now you can get a full size, carry or compact version. Matching slide assemblies are required for some combinations. Soon, Sig intends to release a subcompact grip module and slide assembly. Here’s a summary of the dimensions of the four different grip module and slide assembly options.
With this design, there are lots of options, and you can bet the list of available configuration pieces and parts will only grow.
Let’s take this thing apart
Before I even talk about field stripping procedure or how to swap out grip modules, I should mention a huge feature. You can take down the P320 without pulling the trigger or performing any type of trigger release. Just remove the magazine, lock the slide back, rotate the takedown lever and the slide will move right off the front of the grip module. It couldn’t be simpler and I liked that you don’t have to pull the trigger or manipulate any internal parts before takedown.
A full takedown, required to change grip modules, for example, isn’t much harder. To completely remove the frame from the grip module, start with the normal takedown procedure. Once the slide is removed, simply pull the takedown lever completely out of the grip module, much like you remove the slide release lever on a 1911. Once the takedown lever is completely out, the frame lifts right out of the grip module. No tools and the whole process only takes a few seconds. The best part is that there are no small or loose parts, so there is no risk of “having parts left over” after reassembly.
The most interesting part of the design, apart from the fact that everything can be done without any tools, is that the internal frame and slide assembly are the pieces that lock together. How the frame fits into the grip module really doesn’t have an impact on accuracy. That’s a good thing, as the grip module is made entirely of polymer. More on that later.
Shooting the P320
I shot a broad array of factory .357 Sig ammo through this gun and none of my wimpy hand loads for that caliber. I figured if I was going to run it through accuracy, velocity, and handling testing, I was gonna go with all full-power .357 Sig loads. You know, the ones that the cartridge was designed for to approximate the storied 125 grain .357 Magnum.
The first thing I noticed was the value of a really, really nice grip. The P320 grip feels much like the new one-piece grips on the P226 and P229 models. If you envision a cross section, it’s more of an oval shape than many of the square forms out there today. For me, this results in much more hand-to-grip surface contact and that makes a big difference in felt recoil and ability to control the pistol. I shot this P320 side-by-side with a Glock 32 and Glock 31, both also chambered in the stout .357 Sig caliber, and the comfort of shooting the P320 was far better. My theory is that the squared grips of the Glocks allow the pistol to move around in the hands more as less of the grip surface contacts your fingers and palm.
You’ll notice that both sides of the grip module have a curvy recess above the magazine release button. Use this for your thumb. When I first started shooting the P320, I assumed a high thumb grip similar to how I shoot a 1911. I didn’t really think about the fact that the slide release lever was right in the neighborhood of my raised thumb until I noticed the slide was not locking back after the magazine ran dry. That just might have had something to do with my thumb pressing downwards on the lever. Do the responsible thing – put your thumb in the provides holes and all will be well.
One more thing I noticed while shooting. The bottom of the grip has a cutout on both sides just over the magazine base plate. Presumably, this is to aid manual extraction of the magazine in the event of a jam. The cutouts don’t interfere with your grip but do offer a solid grasp on the magazine if you do need to yank it out with brute force. I didn’t have any jams in the hundreds and hundreds of rounds I fired. That’s one of the things I really like about the .357 Sig caliber – the bottleneck cartridge feeds very, very reliably.
For me, most of the challenge of shooting perfect groups at 25 yards is sight picture. The very slightest of misalignments between the sharp front sight, blurry rear sight, and blurry target can easily translate to a good chunk of an inch (or more) at 25 yards. For that reason, I decided to accuracy test the Sig P320 with a new system I’m testing.
I installed a UM Tactical UM3 Sight Mount. This mount attaches to the M1913 rail in front of the trigger guard, wraps around both sides of the frame and slide, and provides a rail segment above the pistol for an optic or handgun scope. It’s a neat idea and does not interfere with semi-automatic operation.
For my optic, I consulted the gurus at Bushnell. After talking about the scenarios I wanted, we decided on a Bushnell Elite 3500 Handgun Scope. This model is a 2-6x variable with a 32mm objective lens. While it can certainly help you reach out much farther than 25 yards, the variable zoom was perfect for getting a great sight picture at my accuracy testing distance. The reticle is a Multi-X design that offers thick crosshairs that narrow to hair width in the center area. This arrangement gives you precision at the aim point while helping guide your eye quickly to the center of the viewing area.
I shot several boatloads of 5-shot groups with this arrangement and was pleasantly surprised by the accuracy of the P320. In many cases, it even out shot a Sig Sauer P226 .357 Sig that I was using as a comparison. I didn’t expect this result from a polymer frame (sorry, I meant polymer grip module) handgun. The P320’s ability to shoot small groups with a variety of ammo told me that the grip module, frame, and slide assemblies lock together perfectly. Remember, the optic in this scenario was mounted to the polymer grip module and not the slide assembly which you would expect to offer repeatable accuracy. I was impressed.
If you dig .357 Sig, you’re probably a believer in the value every last bit of velocity. After all, the whole point of the .357 Sig caliber is to more or less replicate the performance of a 125 grain .357 Magnum round. Those move at 1,400 to 1,500 feet per second and many believe that’s why it’s been such an effective cartridge over the years.
I tested a bunch of loads for velocity using a Shooting Crony Beta Master chronograph placed 15 feet downrange from my shooting bench. The P320 didn’t disappoint, especially when using Doubletap Ammunition .357 Sig loads. The Godfather of Boom!, Mike McNett, runs Doubletap and he believes in extracting every last bit of performance out of the cartridges he loads. It shows.
Most of the loads shown here were also tested with a Sig P226 and almost without exception, the P320 added a bit more velocity, usually 20 to 30 feet per second. That’s almost certainly a result of the extra .3 inches of barrel length on the P320. The P320 has a 4.7-inch barrel while the P226 has a 4.4-inch barrel.
I’ve got three different models of Sig Sauer pistols in for various reviews and all are chambered in .357 Sig: a Sig P226, P229 and the P320 we’re talking about here. Going into this project, I figured I would love the P226 and P229 and be OK with the P320. It’s a largely polymer gun after all and how can that compare to the classic “steel feel” of the P226 and P229?
I’m trying not to draw comparisons because we’re talking about apples and oranges, except that they share the same caliber, in this case. The most obvious difference is the traditional DA/SA action of the P226 and P229 versus the striker-fired action of the P320. To me, that’s not a better / worse comparison, it’s a personal preference. Being a gun guy, I like both systems for different reasons. The transition from double-action to single-action doesn’t bother me and I kind of like the peace of mind that a first double-action shot offers. On the other hand, I’m not the least bit nervous about carrying a striker-fired gun with a constant, and lighter, trigger press.
The bottom line is that I was very pleasantly surprised with the P320. The accuracy shocked me given its modular construction and polymer grip module. Now I’ve got this idea of keeping it, acquiring a threaded barrel (that’s a P320 option too) and adding a suppressor. Clearly the .357 Sig is not intended to be used with subsonic ammo, I just think it would be a great shooting combination – just like using a suppressor on a hot 9mm pistol. Losing the muzzle blast, even when shooting supersonic ammo, is a really cool shooting experience.
Consistent with my assumptions going in, I figured I would end up sending Sig a check for the P226 and P229 so I could keep them. Now I’m not so sure I won’t be purchasing the P320. Sorry, GunsAmerica Editor Dave, I call dibs.