SIG P320 M17 Review: GU Tested

by Jason Mosher

March 7, 2023



Sig’s M17 is a modern pistol that won the military’s contract for a standard-issue sidearm in 2017. It replaced the (in?)famous Beretta M9 (Beretta 92F) and is only the third standard-issue military handgun since the 1911. While the M17 is based on the P320, there are some slight differences between the two. Let’s run through my SIG P 320 M17 review. We’ll see those differences and examine why the military selected it as their duty sidearm.

Winner of the military’s Modular Handgun System, based on the SIG P320.

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M17 Specs

  • Caliber 9mm
  • Barrel length 3.15”
  • Front sight Single front (optic ready)
  • Rear sight Night sight rear plate
  • Safety Manual 1911 style thumb
  • Trigger Adjustable 4-4.5 lb.
  • Length/Width 4.7”/1.6″
  • Weight 29.6 oz. (no mag)

SIG M17 Background

Sig Sauer began in 1975 and hit the ground running with their P220. Militaries and police around the world have used the P220. But when Glock came along with a lighter gun that held more rounds and was cheaper, the fight was on. Sig was still playing catch-up with Glock when they developed the P320. The 320 was the model Sig used to enter the military’s bid for a modular sidearm. They presented the M17 and won the contract, giving them a much-needed boost in the competitive world of polymer handguns.

The M17 can be purchased on the civilian market for those who want the same version the US military uses. As mentioned above, the interchangeable grip module makes the P320 and M17 stand out from other manufacturers. For a complete lower frame that does not have removable grips, it allows the owner to customize it to their liking. 

Shooting the M17 for a review: gun closeup.
Based on the P320, the M17 has one major feature that most guns do not. That feature is the interchangeable grip module that allows the trigger and frame assembly to be removed and placed into a different grip assembly within minutes.

Sig has a reputation of making good quality firearms. The Sig P320 line of guns has taken their handguns to a new level and the US Military’s contract has helped increase the number of holsters and other accessories available for the P320 and the M17. But how does it stand up to the other big guys in a world flooded with innovative handgun designs? Let’s look at the M17 and see if it is a worthy contender.  

SIG P320 M17 Features

Features of the SIG P320 M17 pistol
1 Military tested

Every handgun is tested and reviewed by someone, but not all of them are tested by designess of the D0D. The Sig M17 has been tested and met all standards set for the MHS.

2 PVD Stainless Steel Slide

PVD is a process of coloring stainless steel and making a super hard durable finish on the outside.

3 Interchangeable Grip Module

The interchangeable grip module can be swapped out in minutes allowing the user to change the size and color of the lower frame.

4 Optics cut-out

The M17 has a removable plate allowing any optic compatible with the Romeo1 Pro to be installed.

5 Picatinny accessory rail

To mount your favorite weapon light under the front.

6 Aftermarket support

Extensive aftermarket support means accessories – like extendos and mag extensions – will be readily available.

Variations of the M17

There is currently just one of significance (the M18), although several aftermarket grip modules are available.

M17 Pistol –  Our Take

Sig’s line of the P320 has only continued to grow after it was released. The M17 model has become popular on the civilian market because of the military’s contract for the weapon. One of the benefits of the Sig M17 is the extensive testing it undergoes during the selection process. This does not mean that other models did not undergo the process as well, but it does mean the M17 has been proven to be reliable. While it is based on the P320 platform, lets break it down and see what the differences are.

M17 out of the box

The M17 comes standard with a coyote PVD finish on the slide and coyote tan on the grip module. It comes with three magazines, one 17 round, and two 21 round extended mags. If you are wanting an optic, the slide is pre-cut for any Romeo1 PRO compatible optic. All you need to do is remove the two set screws holding the plate on, and the optic is ready to install.

SIG M17 and mag, fresh outta the box.

One thing I like about the M17 is that it has a different look than the standard all-black handgun most manufacturers are spitting out. Choosing to do two shades of brown gives the gun a nice look. It retails in the $649.99-$800 range depending on the accessories included in the case. The grip module can be changed for a different color, but it would be nice to see some other colors on the slide someday too.  

Because of the military contract, there are plenty of holster options and other accessories for the M17. This is something I always look at before purchasing a handgun. It can be problematic to buy a weapon and have no options for holsters. I like the trigger on the M17 a little better than the Glock 17 trigger. It is smooth and has a crisp break. The M17 doesn’t come standard with a threaded barrel, but aftermarket barrels can be purchased for it.


There are some slight differences between the P320 and the M17. This included the iron sights and optic cut-out on the slide, but the biggest difference was the manual safety. The M17 has a 1911 style safety that makes the interchangeable grip safety different as well. Other parts are the same as the P320, but if you want a different grip module, it will have to include the cut-out for the safety.

M17 review: on the range with the military's P320-based MHS.

There are options out there, just not as many as there are for the P320. I found a Wilson Combat grip module that works with the M17 for under $100. The grip module that comes standard with the M17 however is comfortable, and I found myself switching back to it.

Holding the M17 reminds me of a 1911. This is mostly because of the way the slide and grip are orientated along with the thumb safety and slide release. It has that natural feel of pointing that you see with a 1911 as well. The 1913 Picatinny rail has plenty of room for most handgun-mounted flashlights.

SIG P320 M17 Wilson Grip Module.
SIG P320 M17 equipped with Wilson Grip Module.

The texture on the grip portion of the lower frame is light. I don’t like to have sandpaper on my grips, but I would have liked to see a little more texture on the sides and back portion of the grip.      

Reliability & Accuracy

Most newer handguns being produced are much more reliable than they used to be. When they do have issues, it’s usually hollow-point ammo they don’t like. I have fired a lot of FMJ out of the M17 but not as many HP rounds. Testing a gun’s ability to eat ammo is never boring. I rounded up a few different types of HP ammo and headed to the range. I stuck with the most popular brand: Sig, Winchester, and Hornady. I fired a total of 300 HP rounds through the M17 and didn’t encounter any issues. This didn’t surprise me with the extensive testing that has already been done since the M17’s release.

Carrying the SIG P320 M17 shows its size.
Petite, it ain’t.

There are some handguns out there I would call reliable for self-defense, but this thing is ready for battle. The accuracy of the M17 is what you would expect from a quality gun with a 5-inch barrel. I was able to hit metal targets out to 75 yards easily and keep good groups on paper out to 30 yards. With a red-dot, accuracy on this thing would be even better.    

SIG P320 M17 Pros and Cons 

  • Reliable – Never fails to go bang when you pull the trigger
  • Optic read – nNt as novel a thing as before; all but necessity now
  • Interchangeable– Grip modules are a great multiplier
  • Thumb safety – Reminiscent of the 1911
  • Monochromatic – No color options for finish
  • Limited modules– Limited grip modules for the M17/M18 versions
  • Higher end– Not top-shelf price but not budget-friendly either

Report Card


Unless you have small hands, this thing is easy and fun to shoot.


No malfunctions with any type of ammo I fired through it.


I would like to see just a little more texture on the grip, but the gun feels natural in your hand.


The longer barrel helps with accuracy and the trigger pull was smooth and light.


You get what you pay for. The M17 is a little on the high end but you get a quality, durable gun.

SIG P320 M17 Final Grade

Our Grade


Reviewed by Jason Mosher

Reader’s Grade


Based on 7 Reviews

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I used mostly American Eagle 115 grain target for range ammo. I prefer Hornady Custom 125 grain HP for a defensive load.

Other options include:

Range Rounds


MagTech 9mm 115 GR FMJ Ammo

Cost Per Round
Natchez Shooter’s Supply $0.24
Palmetto State Armory $0.34

Self Defense Ammunition

Box of Hornady 9mm pistol ammunition

Hornady Critical Defense 115 GR

Cost Per Round
Cabela’s $1.24
Midway USA $1.24

M17 Accessories

There are a few things I’d recommend for the M17, starting with the Wilson Combat Grip Module for M17 – Black and a Safariland Level One Retention Holster. If you are interested in some holster customization options, the Modular Holster Adapter is worth a look.

Some others include the following. Remember: make sure your preferred holster will fit the WML and optic on your gun.

M17 Accessories

SIG Romeo Pro
  • Motion activation system
  • 20,000 hour run time
  • 5-year warranty
On Amazon
X300 UWeapon Light
  • 1000 lumens
  • TIR lens for far-reaching light
  • Attaches with Universal and Picatinny rails
On Amazon
Streamlight TLR-2
  • Flashlight/red laser combo
  • 1,000 lumen output
  • 283m beam range
Check price
Paragon Optic Cleaning Lens Cleaner
  • Clean your optics and weapon light lens
  • 5ml Weapon Light Cleaner
  • 10ml Optic Lens Cleaner
  • Micro Fiber Cloth
Check price
The first half of
  • Proper eye protection is critical and should always be worn
  • Ballistic rated, not just sunglasses
Compare top eyepro
The second half of
  • Ear protection is also critical. Protect your hearing!
  • Many styles (some stackable) are available
Compare best earpro
Appropriate cleaning kit
  • For cleaning, care, and maintenance
  • Not all kits are created equal
Compare top kits
Dark Angel D.A.R.K. Trauma Kit
  • You should always have medical gear when shooting (any gun)
  • External Tourniquet for easy access
  • Pull handle for rapid deployment
  • Vacuumed sealed insert to keep your contents protected
  • Kit content scalability
Check price
Handgun Master Cleaning Station
  • Fits .22 to .45 as well as some oddball cartridges.
  • Wide range o
  • Fits .22 to .45 as well as some oddball cartridges.
  • Wide range of tools for maintenance and cleaning.
  • Big work area but stores small.
  • Tools for maintenance and cleaning.
  • Big work area but stores small.
Check price
Suitable biometric safe
  • Biometric scanners are a plus but only one 0ption
  • Securing an off-body handgun is paramount
Compare biometric safes

SIG M17 Maintenance

A reliable handgun requires regular maintenance and cleaning, but you have to know how to break it down in order to do so. Take a watch at this:

Suggested Resources For You And Your SIG P320 M17


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About Jason Mosher

Jason has been serving as a County Sheriff in Missouri since 2013 and worked as a Police Chief prior to that. He is a Tactical Firearms Instructor, Armorer and Generalist Law Enforcement Instructor. Jason is a writer in the firearms industry and likes to study the history of guns and their inventors.

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