How did the SIG P320, which was only introduced to the market in 2014, beat Glock, which has a long history of proven performance in civilian, police, and military use? The answer is that of the candidates, it was really the only truly modular pistol. The Army was looking for a system handgun, one that could be easily maintained, and be adapted to many roles and to a diverse user pool. Consider that in December of 2015, all combat roles were officially opened to females.

To the left is a field stripped SIG P320. Field stripping the SIG takes about a minute and requires no tools. The “gun” is actually that silver piece of metal with the trigger attached. The grip is just a plastic shell. The fire control unit, aka the chassis, is the serialized piece. The serial number is visible through a window on the right side of the plastic grip module when the pistol is fully assembled.

The grip frame is available in three circumference sizes, small, medium, and large. Each M17 (the military model designation of the new standard service pistol) is shipped to the Army with all three grip sizes. Issued pistols can be sized to fit the individual soldier.

You will notice some differences between the M17 in the soldier’s hand above, compared to the photo of the field stripped P320. The stripped gun is the commercial P320 FDE Compact (FDE = Flat Dark Earth). This gun has greater similarity to the second variant of the P320 that was adopted by the Army, the M18.

The basic commercial P320 comes in the following configurations:

 
There is the new X-series of competition and tactical pistols, but let’s ignore those for this discussion.

The M17 is actually a hybrid of the standard commercial configurations. Both the M17 and the M18 use the Carry grip size, so with a flush fit magazine, they both hold 17 rounds of 9mm. However, the M17 uses the Full Size slide with the 4.7” barrel. The M18 is basically a Carry configuration pistol with the Compact length slide and barrel (3.9”), and the Full Size (17 round) grip length

Other features of the military models are that they come equipped with an ambidextrous frame mounted manual thumb safety. Each military pistol ships with one 17 round flush fit magazine, and two extended length 21 round magazines. They are also equipped with a removable plate on top of the slide, cut specifically for the Leupold DeltaPoint Pro miniature red dot sight.

Currently, the Compact is the only standard commercial model available in FDE as a whole gun. I can easily configure my Compact model to more closely match the M18 by buying a FDE Carry grip module, available today at Midway USA for $36. The extended mags with the FDE bottom are not commercially available — nor are flush fit mags with an FDE baseplate – only black. My Compact came with two 15 round flush fit magazines with black baseplates. Also, Full Size slide and barrel assemblies are not available in the FDE color to make a M17 look-alike.

But fear not, SIG has announced that somewhere around the May 2018 time frame, they will bring to the commercial market around 5,000 M17 replicas, for those fanboys collectors that need to have a military replica.

So what kind of parts or kits are available? For starters, SIG sells magazines, barrels, both standard and threaded, and grip frames in various sizes, circumferences, and colors. Commercially, whole guns are sold only with the Medium grip circumference size. If that doesn’t work for you, you can opt to buy a different grip, though availability of every conceivable option is spotty.

Then there are the “Caliber X-Change Kits”. These are basically the whole gun, including one magazine, but without the chassis (the legal “gun”). The available calibers are 9mm, .357 SIG, and .40 S&W. You can even go from a Full Size, all the way to a Subcompact. There is a .45 ACP P320, but you can only change sizes. You can’t change calibers because the .45 P320 is a beast of its own.

The P320 has certainly had some teething problems. The P320 was SIG’s first striker-fired pistol. When the pistol was designed, SIG decided NOT to include a tabbed or hinged trigger safety as is common on almost all other striker-fired pistols. In August of 2017, Omaha Outdoors, an online gun shop that sells hunting, camping, fishing, and shooting supplies, posted a video on YouTube that quickly went viral, demonstrating that the SIG P320 could reliably be made to fire by dropping it on a hard surface, to land on the back of the slide and the beavertail. This came to be known as the “-30° drop angle.”

Commercial SIG P320 FDE Compact

Omaha Outdoors surmised, and SIG Sauer confirmed, that the problem was due to the mass of the trigger itself, and of another part internal to the trigger assembly. The momentum of the trigger mass when the gun suddenly stopped when it landed on the back of the slide, caused enough backward trigger movement to fire the gun.

This was an enormous black eye for SIG. They went into immediate action to announce, not a recall, but a “voluntary upgrade.” SIG’s public position is that the gun had met all industry standard and government mandated drop safety tests as originally designed. Since there is no standard drop safety test that required a drop at the “-30° drop angle,” the gun really is safe, so they say.

Nevertheless, the “voluntary upgrade” program includes SIG picking up shipping costs both ways from and to the customer, the installation of new low mass trigger components, and the addition of a new out-of-battery disconnector system which involves milling a small slot in the bottom of the slide.

Production was immediately halted at the time, so that all guns in production were given the upgrade before they left the factory. Any gun that you buy today at the gun shop will have the upgrade.

The photo up above of the M17 and M18 together, show these guns with the old high mass trigger. In November of 2017, the 101st Airborne Division at Fort Campbell, Kentucky became the first Army unit to receive M17s and M18s. Photos of the guns that were delivered show that they had been upgraded with the low mass trigger. It may be a little hard to see, but the photo nearby of my commercial P320 FDE Compact shows what a low mass trigger looks like. For more details, see:
https://www.sigsauer.com/support/p320-voluntary-upgrade/

An interesting aside concerning the MHS competition is that SIG had a partner in its submission. That co-winning partner was Winchester ammunition. Since one of the criteria was enhanced lethality, Winchester submitted two types of ammunition, the XM1152 FMJ ball, and the XM1153 “Special Purpose” ammunition. The XM1153 is a hollow point round.

Apparently, Army lawyers have made a law of war determination which allows the U.S. to begin using hollow point ammunition. Previously they had decided that Open Tip Match (OTM) rifle ammunition was OK. Now they have decided that it is OK for the US to field expanding hollow point pistol ammunition. As I understand the justification, it is because hollow point ammo is less likely to endanger innocents through over-penetration or ricochet, and that HP ammo will reduce suffering through quicker expiration of the enemy. Besides, we never signed the 1899 Hague Convention anyway! Or something like that.

Another interesting point is that the Army plans to issue the M17/18 to many more troops than were previously issued handguns. The plan is that soldiers down to the team leader level will be issued handguns. A team is typically composed of 4 soldiers and is a subset of a squad. The team leader is normally a sergeant.

So how does my Sig P320 shoot? I guess about as good as I can shoot any striker-fired pistol. I’ve never owned a Glock, but I have had an S&W M&P .40 for a couple of years. Most of my handgun shooting experience is single action mode, whether with revolvers or autopistols. I must confess my striker pistol shooting skills are pretty weak.

Striker pistols are easier to shoot than true double actions. The trigger pull on the P320 is in the mid-6-pound range, about average for striker pistols as I understand it. My biggest challenge is learning to smoothly pull the trigger through, while keeping the sights on target. My experience with single action triggers has spoiled me with the almost instantaneous trip of the trigger when I want to fire. I must consciously think through keeping a smooth constant pull on the longer stroke of the striker trigger.