Skip to main content

Smith & Wesson Adds 5.7x28mm Caliber to M&P Line

Smith & Wesson jumps into the 5.7x28mm market with a well-designed version of its M&P pistol. Keith Wood gives us a full review.

Smith & Wesson Adds 5.7x28mm Caliber to M&P Line

I’m not picking on Smith & Wesson when I say it has not been at the forefront of handgun development for the past few years, opting instead for an incremental approach to innovation. That changed this year when the company introduced the M&P 5.7, a semiautomatic handgun chambered in the high-performance 5.7x28 cartridge. The 5.7 is not simply another M&P variant; this handgun incorporates some unique features that have tangible effects on its performance.

Smith & Wesson’s take on the 5.7x28 pairs a stainless steel slide with a full-size polymer frame. Though the M&P 5.7 shares the overall look and several features with the rest of the M&P line of handguns, there are some significant design departures as well. For starters, this is not a striker-fired handgun but rather a single-action with an internal hammer. More on that later. The locking system is different as well, using a gas-operated locked breech.

Why the departure from the M&P’s usual operating system? Building a handgun chambered in this cartridge is not as simple as it sounds.

Smith and Wesson MandP in 5.7x28mm trigger and controls
The M&P 5.7 is available with or without a thumb safety. The flat-face trigger was impressive, breaking cleanly at 3.5 pounds thanks to the internal hammer system.

The 5.7x28 operates at significantly higher pressure than traditional handgun cartridges. As an example, the 9mm +P is limited to 38,500 psi while the 5.7x28 operates at more than 50,000 psi. That increase in pressure can cause design challenges in a semiautomatic handgun. Smith & Wesson’s engineers tackled this problem by effectively delaying the cycling of the action using what they call the Tempo Barrel System.

On the M&P 5.7, the breech remains locked until the bullet passes a gas port located near the muzzle. That gas is then channeled rearward, camming open the two-piece rotating barrel assembly and allowing the breech to unlock. This minor delay allows the slide to avoid cycling during the peak pressure curve. The pause also allows slower-burning powders to ignite fully before the system unlocks. The timing is imperceptible from the shooter’s perspective.

The slide is machined from stainless steel and, like all the metal components, is treated with the firm’s black nitride-style Armornite finish. The slide is long and noticeably narrower than that of an M&P 9mm. There are deep cocking scallops both at the rear of the slide and just forward of the ejection port.

Smith and Wesson M&P in 5.7x28mm barrel assembly
The M&P 5.7 uses a unique locking mechanism that includes a two-piece barrel assembly, part of the gun’s gas-operated design.

The slide is optics-ready, with its mounting surface protected by a removable cover plate. I chose not to mount an optic during testing, relying instead on the quality drift-adjustable, three-dot iron sights.

The top of the slide is serrated, and two longitudinal cuts are present near the muzzle to achieve the optimal weight for reliable cycling. The extractor is external and works in conjunction with a fixed ejector found on the frame. The recoil spring assembly mates a steel guide rod with a flat-wire spring.

The Tempo barrel measures five inches and uses a 1:9 twist. The barrel is threaded 1/2x28 at the muzzle, allowing for the attachment of suppressors compatible with that pattern.

As I mentioned, the barrel is a two-piece assembly thanks to the unique locking mechanism. The rifled inner section is effectively a gas piston that rides inside the outer tube. The two components connect via a cammed locking lug that rotates into position. The integral feed ramp is generously sized and polished for feeding cartridges smoothly into the chamber.

Smith and Wesson MandP 5.7x28mm slide lightening cuts
The slide has lightening cuts in the top. The five-inch barrel is threaded 1/2x28 and comes with a removable thread protector.

The polymer frame on the M&P 5.7 is designed around the long overall length of the 5.7x28 cartridge. This means the grip is longer than it would be on a 9mm or a .45 but also narrower. The grip is textured and, unlike other M&P variants, there are no user-configurable backstraps. I found the grip to be comfortable in the hand, probably because its size and shape are somewhat similar to those found on a 1911. There is a Picatinny accessory rail located on the dust cover of the frame.

Polymer-frame guns have become the mainstays for personal defense, but they do have their shortcomings—particularly the triggers. Since the M&P 5.7 is not striker-fired, it doesn’t suffer this malady. The handgun has an internal hammer and operates as a single-action semiauto. Think of a 1911 without an external hammer.


The result is a great trigger that, on my test sample, broke cleanly at 3.5 pounds. Reset is short, and there is an overtravel stop molded into the frame. The M&P 5.7 is available with or without a manual thumb safety, and there is a trigger-bar safety. The slide stop is ambidextrous, and the magazine release is reversible.

Disassembling the M&P 5.7 is fairly unique. First, remove the magazine and ensure the handgun is unloaded. The slide is then retracted and held in position where the correct portion of the slide stop aligns with the takedown notch. This can be a bit tricky at first. Then, a punch, a bullet tip or even a paperclip can be used to depress the slide stop pin visible on the right side of the frame.

Smith and Wesson MandP 5.7x28mm 22-round magazine and speed loader
The steel-bodied magazine holds 22 rounds, and a handy mag loader is included with the pistol.

Remove the slide stop from the left side of the frame; the right lever will stay in place. The slide assembly can now be removed from the frame, and there is no need to dry-fire the handgun to do this.

Remove the recoil spring assembly from the slide, and once the locking lug is rotated clear of the abutment in the slide, the barrel is free. Rotating the breech section of the barrel unlocks it from the outside shroud, completing the disassembly process. It sounds more complicated than it is.

The M&P 5.7’s magazine uses a steel body that allows it to be made narrower than a polymer-body mag. The dual-column magazine holds 22 rounds, giving the pistol a 22+1 capacity with a round in the chamber.

Fully loading the magazine takes a bit of effort, so a simple polymer mag loader is included with the handgun. The base pad on the magazine is polymer, as is the highly visible follower. The follower can actually be seen through the slide stop notch with the magazine seated, which provides a visual clue as to the condition of the chamber.

The M&P 5.7 is a great deal of fun to shoot. Despite lots of velocity, recoil is extremely light. The recoil sensation is similar to that of a .22 Magnum handgun. The 5.7x28 round is extremely flat-shooting, and hits on 200-yard targets are practical once you know how much to hold over. Recoil is light enough that spotting bullet impacts at longer distances is feasible. Due to the performance characteristics of the round, use caution with steel targets at close range. Treat it more like a carbine than a handgun in that regard.

My ability to truly evaluate accuracy was limited because I was able to get only one load: Fiocchi’s 40-grain Hyperformance. The gun shot well, and my groups would likely have improved had I chosen to mount a red-dot optic.

Smith and Wesson MandP 5.7x28mm Accuracy Chart

Reliability was 100 percent, and average velocity was within nine fps of the advertised data for this particular load. Much of the load data for the 5.7x28 uses a 10-inch barrel, so it was good to see this kind of velocity from a handgun-length bore.

Out of curiosity, and since the barrel was threaded, we mounted a Gen 1 SilencerCo Osprey to the M&P 5.7 to test function. The Osprey is set up with a Nielsen device, designed to ensure suppressor reliability with traditional semiauto handguns. Would the unique locking system cause any issues with a suppressor mounted? The answer was no; it functioned as normal. Subsonic ammunition is available from Fiocchi, which would add to the utility of mounting a suppressor to this handgun.

The 5.7x28 isn’t for everyone. Ammunition choices are few, and prices are high. However, Smith & Wesson’s M&P 5.7 makes a great host for this cartridge, combining quality construction, high capacity and great shootability.

If I were allowed only one handgun, it wouldn’t be chambered in this cartridge. That said, we live in America and can have as many guns as our budget allows. For the shooter looking for something different in terms of performance, the 5.7x28 is a fun-to-shoot and attractive option.

Smith & Wesson M&P 5.7 Specifications

  • TYPE: Striker-fired semiautomatic
  • CALIBER: 5.7x28
  • CAPACITY: 22+1
  • BARREL: 5 in.
  • LENGTH/WIDTH/HEIGHT: 8.5/1.1/5.25 in.
  • WEIGHT: 1 lb., 10.7 oz.
  • CONSTRUCTION: Stainless steel slide, polymer frame
  • GRIPS: Textured polymer
  • TRIGGER: 3.5 lb. pull (measured)
  • SIGHTS: Three-dot, drift-adjustable rear; optics ready
  • SAFETY: Trigger (as tested)
  • PRICE: $699
  • MANUFACTURER: Smith & Wesson;

Why the 5.7x28?

Box of Fiocchi 5.7x28mm ammunition
The 5.7x28 was the result of NATO’s desire for a more effective cartridge than the 9mm.

More than two decades ago, NATO sought to replace the aging 9mm Luger with a new cartridge designed for use in both handguns and personal defense weapons (PDW). The organization sought a lightweight, high-performance round that would be effective beyond traditional handgun ranges and could defeat body armor.

It narrowed its choices to the 5.7x28, developed by FN Herstal, and Heckler & Koch’s 4.6x30. The original 5.7x28 production cartridge used a 31-grain bullet and produced 2,350 fps of velocity from the FN P90 10.3-inch barrel.

With a .224-inch bullet, comparisons to the .22 Hornet aren’t far off the mark. This tiny round packs a serious punch, at least in terms of speed. Due to some international politics the 5.7 wasn’t officially adopted by NATO until 2021, but the bottleneck cartridge has nonetheless enjoyed some popularity, particularly in military and law enforcement circles.

For many years, the only commercially available 5.7s in the U.S. were the FN P90 and FN Five-Seven along with some AR-style variants made by smaller manufacturers. That has changed, and today several makers, including Ruger and Smith & Wesson, chamber handguns in the cartridge.

Ammo choices have expanded as well with Fiocchi, FNH, Federal and Speer all offering 5.7x28 factory options. Current factory bullet weights range from FN’s 27-grain load to Fiocchi’s 62-grain subsonic variant, although most options use a 40-grain projectile. None of the commercially available loads are considered armor-piercing by ATF.

Ammunition for the 5.7x28 is expensive, averaging nearly $1 per round, and reloading for the cartridge presents some significant technical challenges.

GET THE NEWSLETTER Join the List and Never Miss a Thing.

Recommended Articles

Recent Videos

Scott Rupp and Richard Nance correct some common shooting advice.

Smith & Wesson M&P in 5.7 and .22 Mag. Calibers

Scott Rupp and Richard Nance correct some common shooting advice.

Streamlight Updates Its Wedge Flashlight with Tail Cap Switch

Scott Rupp and Richard Nance correct some common shooting advice.

Hodgdon Adds Match and HD to Its Winchester StaBALL Powder Line

Scott Rupp and Richard Nance correct some common shooting advice.

Crossbreed Rogue Holster and System with Mag Carrier

Scott Rupp and Richard Nance correct some common shooting advice.

Smith & Wesson Model 350 Hunting Revolver In .350 Legend

Scott Rupp and Richard Nance correct some common shooting advice.

First Look: Taurus GX4 XL

Scott Rupp and Richard Nance correct some common shooting advice.

A Perfect 10? The S&W M&P 10mm

Scott Rupp and Richard Nance correct some common shooting advice.

S&W M&P Shield Plus

Scott Rupp and Richard Nance correct some common shooting advice.

A Perfect 10? The S&W M&P 10mm

Scott Rupp and Richard Nance correct some common shooting advice.

Beretta A1 Carry

Scott Rupp and Richard Nance correct some common shooting advice.

First Look: Federal .30 Super Carry Pistol Cartridge

Scott Rupp and Richard Nance correct some common shooting advice.

Bad Shooting Advice

Handguns Magazine Covers Print and Tablet Versions

GET THE MAGAZINE Subscribe & Save

Digital Now Included!


Give a Gift   |   Subscriber Services


Buy Digital Single Issues

Magazine App Logo

Don't miss an issue.
Buy single digital issue for your phone or tablet.

Buy Single Digital Issue on the Handguns App

Other Magazines

See All Other Magazines

Special Interest Magazines

See All Special Interest Magazines

GET THE NEWSLETTER Join the List and Never Miss a Thing.

Get the top Handguns stories delivered right to your inbox.

Phone Icon

Get Digital Access.

All Handguns subscribers now have digital access to their magazine content. This means you have the option to read your magazine on most popular phones and tablets.

To get started, click the link below to visit and learn how to access your digital magazine.

Get Digital Access

Not a Subscriber?
Subscribe Now

Enjoying What You're Reading?

Get a Full Year
of Guns & Ammo
& Digital Access.

Offer only for new subscribers.

Subscribe Now