Review: Sig Sauer M18

You all know about the U.S. Military picking the M17/M18 versions of the P320 as their next sidearm. To sum it up quickly, the U.S. Army and U.S. Air Force hosted a competition to select their next handgun. The M9 has been coming to the end of its service life and the US Military needed something that was modular. Thus the XM17 Modular Handgun System competition was brought to fruition. To make a long story short, SIG Sauer won with their P320 platform. They chose the M17 and the M18.

The M17 and M18 are the P320 Full Size and Compact with a full size grip, manual safety, as well as a Coyote PVD finish. We grabbed the M18 as we were interested in carrying it concealed.

Why did they pick the P320 Platform?

To really understand what’s so interesting about any of the P320 line of pistols, you’ll need to disassemble one completely. It’s almost entirely tooless. The entire Fire Control Unit pops out by removing the giant takedown pin, leaving just a polymer frame behind. The slide can be almost stripped completely by pushing in on the extractor pin from the rear.

Basically every single wear part can be accessed and replaced in minutes out in the field. Additionally you can tailor the firearm to the shooter. Need a more concealed carry oriented grip? Pop the Fire Control Unit out and put it in a smaller frame. Then toss your slide back on and you’re good to go. If you consider this from an armorer’s perspective, this firearm makes a ton of sense. No hammers, no roll pins. The most advanced tool you really need for your wear items is something to push that extractor pin in to remove the rear cover. All of this drastically improves the service life of these pistols.


It makes a lot of sense that it won the MHS competition and frankly it’s proven to be a net positive for the consumer. Especially because SIG SAUER had the foresight to make just the Fire Control Unit hold the serial number, making it the only part that’s legally a firearm. This means that the polymer grip module isn’t a firearm and can be shipped right to your front door. 


Our M18 shipped in the standard grey plastic SIG box you’ve come to know along with two 21 round magazines as well as a flush fitting 17 round mag. The 21 rounders are full blown mags, and aren’t extended via the base pad. A base pad provides some extra stippling as well as a flare at the bottom to make stripping the mag quicker. Further aiding in stripping mags, there are two cut outs on both sides of the grip that you can get your fingers into. Great for doing tactical reloads where you are putting your empty mags back into your plate carriers or mag pouch as well as if your mags become gritty. However the mags do drop free by themselves if your intent was to just drop them to the ground.


SIG included a set of SIGLITE night sights that are pretty good to go out of the box. They glow like you’d expect them to. The front has a white ring around it, and the rear has a black ring. With an optics platform standard on the M18, you’re pretty set out of the box to slap a Leupold Delta Point Pro as well as the SIG Romeo1Pro. You’ll notice that there are no screws on the top holding down the optic plate, as SIG hid them underneath. You’ll have to remove the extractor pin to reach them. If you’re anything like us, you’ll immediately tear the pistol apart to slap an optic on there without looking into it at all. If you’re really like us you’ll let the loaded chamber indicator fall out and immediately lose the spring. 

Shooting the M18

We ran ~500 rounds through the M18 during our time with it, and walked away pretty pleased with it. Accuracy is right where it should be- the pistol is more accurate than we are. Holding tight groups when taking our time was easy, and maintaining that during fast paced drills was smooth. Is it a tack driver like a 1911? No, it isn’t. However it is just as accurate as a Glock or any other combat handgun. The included SIGLITE sights are reasonable - enough to keep track of when making long strings of quick shots at the very least. Ideally if we were to run only irons, we’d probably prefer white rings round rear tritium vials, however that’s mostly personal preference.


Ergonomics of the M18 are great. With a pretty aggressive grip texture, you’ve got no issue holding on tight. One of the most striking things to us was the fantastic design of the manual safety. In 2020, manual safety options are mostly non-existent in striker fired pistols however it was one of the requirements of the MHS competition. For those that don’t regularly train with a manual safety, it can take a bit of work to get the hang of. However the M18 is one of those few exceptions as the safety is super easy to deal with. If you’re someone who runs their pistol with their thumbs forward, the M18s manual safety won’t be much of an issue for you. A quick movement of the thumb on the draw and you’re ready to roll without having to adjust your grip. Overall, the controls on this gun are thoughtful and well placed. The slide stop has a nice lip to prevent you from hitting it if you have a high grip, which is a problem on a lot of other platforms.


Alright so how’s the trigger? The M18, much like the P320, is on the heavier side out of the box. Ours came in at about 6 Pounds. Despite that it has a very short pull and you can hit the wall very quickly.. The reset is on the longer side however it’s plenty tactile, giving you that audible click. Ultimately it’s easy to shoot fast with the M18 because the trigger is consistent and easy to learn. We find that as long as a trigger is predictable and tactile there is no reason you can’t run it fast. .18-.2 split times were easily achieved for us without much work.



We fed the M18 a mix of ammunition and didn't experience any malfunctions. It shot everything from 135 grain Hornady Critical Duty, 115 grain Winchester White Box,124 grain Speer Lawman, and some other mix matched ammo. Overall we ran about 500 rounds through the M18 without cleaning it.The only minor hiccup we had was mostly self inflicted. When moving optics around, we didn't tighten down the optics plate well enough when we put it back on. This led to the rear sight coming loose. Because the M18 is so easy to take apart, we could easily tighten it back up at the range. However in our experience, a small dab of blue loctite can go a long way.


The M18 is obviously a really innovative platform. Modularity is supreme with the P320 platform and we hope that other firearms makers follow suit. It feels like the future. The added benefits of shipping grip modules right to your front door is such a cool perk. It also appears that SIG has been happy to let the market roar with all sorts of makers coming up with frames. They’re even releasing the Fire Control Unit as a separate item in the coming months, which means you can order every part of the P320 platform separately.

On our end, it’s a performer. It makes sense why the Military went with the M17 and M18 especially when you consider it from the standpoint of making a firearm last 30+ years of service. They have a high level of modularity in their rifles and there’s no reason they can’t have that in their pistols as well.

Should you get one? If you’re content with a manual safety and you like the P320 line then you’d be satisfied. The Coyote PVD finish is super cool, and the firearm is well featured. It’s a great firearm and rather fun to work with.

Holsters for the SIG Sauer M18 can be found here