The FN 5.7×28 Round Explained

The FN 57x28mm Round pictured.
August 4, 2023  
Categories: Learnin'
Although it has been around for nearly 30 years, the FN 5.7×28 round has become increasingly popular among shooters for personal defense, light varmint hunting, and casual target shooting.


Fabrique Nationale Herstal (FN Herstal or FN) developed the 5.7x28mm round in the late 1980s for use in the FN P90 Personal Defense Weapon (PDW). The intent was to develop a high-velocity round to replace the 9mm Parabellum for NATO.
An FN 5.7x28 pistol pictured.

The pistol for which the FN 5.7x28mm round was created. (Photo credit: FNH)

While some have compared the round to 22 Magnum or 22 Hornet, it is a completely different animal. Unlike most common types of ammunition, it has no parent case. FNH designed it from the ground up for its purpose.

When first introduced in 1990, the 5.7×28 was designated SS90 and fired a 23-grain plastic core bullet with a muzzle velocity of 2800 feet per second (fps) from the 10” barrel of the FN P90. It should be noted as a general rule across ammunition types that when fired from a shorter 6” barreled pistol the loss in velocity is about 200 fps. When using a 16” carbine, the velocity increased by 300 fps.
Three FN 5.7x28mm Rounds, one with a metal tip and two with polymer tips

Three 5.7×28 rounds: one full metal jacket and two with polymer tips.

In 1993 an improved version debuted, known as the SS190. It was 33-grain bullet that was seated slightly deeper in the case and intended for a semi automatic pistol, the FN Five-SeveN. The round used a steel and aluminum core instead of the original plastic one. SS190 supplanted the original SS90 round.


According to NATO tests, the 5.7×28 proved superior in performance to 9mm Luger. The recoil is 1/3 of that of the 9mm. Additionally, the rounds weigh 1/3 less of a 9mm cartridge and theoretically allow troops to carry more ammunition.
Penetration of various materials, including soft body armor, left 9mm in the dust. Viewed as a self-defense round within a military context where a hollow point or expanding ammunition types were against the protocols of the Hague Convention, over-penetration was not bad. The P90 was definitely on track as the latest next-generation PDW for support troops and personnel. They may not have needed a full-sized service rifle, but maybe something more powerful with a greater feed capacity than a typical service pistol.
FN states the round’s ideal range is within 250 yards with a maximum range of 1800 yards from the P90. Out of a pistol, this changes to about 50 yards with a maximum of 1500 yards. FN coats the rounds in a thin layer of polymer to aid in feeding, case extraction, and ejection. This greatly helps with regard to reliability.
In addition to numerous military units, many law enforcement agencies, including the Secret Service, selected both the P90 and FN Five-SeveN.
FN P90 5.7mm in Tripoli

5.7x28mm FN P90 with integrated Ringsights reflex sights. This image was reportedly taken by a member of a pro-Tripoli militia somewhere in Libya in 2018. There were reportedly fewer than 400 FN P90s imported by the Gaddafi regime before the Libyan Civil War kicked off in 2011.


Where to Find Your 5.7×28 Ammo For Sale

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Lookin’ for 5.7 ammo for sale? Here ya go!




Non-Military Roles

On the civilian side, the FN 5.7x28mm round has proven very popular over the past 15 or so years. FN had to redesign the P90 to meet importation standards in the US. FN lengthened the barrel to meet requirements without running afoul of National Firearms Act (NFA) restrictions.
Perhaps even more popular are the handguns chambered in 5.7, such as the original FN Five-SeveN, Palmetto State Armory Rock, and Ruger’s Model 57. Several manufacturers offer AR-15-style rifles and upper receivers chambered in 5.7 x 28mm. Some use the original 50-round magazine of the P90 or its civilian counterpart, the PS90. Newer incarnations use the pistol magazines of the FN Five-SeveN pistol, and perhaps the Ruger pistol magazine may be offered in the future.
While not intended as a hunting round beyond its use on small varmints, some rounds are loaded with a 40-grain Hornady V-Max bullet with a polycarbonate tip that aids in expansion.


The biggest complaints from shooters have been both the cost of ammunition and the lack of support on the reloading side. Pre-pandemic, a 50-round box of 5.7×28 ammo cost between $20 and $30. Over the past year, the price has soared tremendously. In time, the price should come down again, but this has never been an inexpensive round to shoot.
A major concern regarding a pistol chambered in high velocity 5.7 is the risk of overpenetration in a civilian defensive situation. This risk may be overhyped, however, as the bullet does not retain much energy due to its light weight while passing through a solid target. In fact, it carries less than half the energy of a typical 9mm bullet beyond 200 yards.
A box of FN 5.7 x 28mm rounds

(Photo credit: FNH)


Whether you collect military-style firearms or are simply a fan of a high-performing, somewhat specialized round, the FN 5.7x28mm may have something to offer you as a shooter. It is important not to downplay or overplay its performance, but rather to keep in mind the purposes for its design.
Mike Searson

Mike Searson

About the Author

Mike “the Mook” Searson is a veteran writer who began his career in firearms at the Camp Pendleton School for Destructive Boys at age 17. He has worked in the firearms industry his entire life, writing about guns and knives for numerous publications and consulting with the film industry on weapons while at the same time working as gunsmith and ballistician. Though seemingly a surly curmudgeon shy a few chromosomes at first meeting, Searson is actually far less of a dick and at least a little smarter than most of the Mad Duo’s minions. He is rightfully considered to be not just good company, but actually fit for polite company as well (though he has never forgotten his roots as a rifleman trained to kill people and break things, and if you look closely you’ll see his knuckles are still quite scabbed over from dragging the ground). You can learn more about him on his website or follow him on Twitter, @MikeSearson.


  1. GomeznSA

    Replying to Chuck – there have been cases where the 5.7 has been used against people, most notably at Ft. Hood – it proved to be devastating.

  2. Chuck

    Like the idea of carrying 22 rounds in a pistol sized firearm. Twenty-three if one is pre-staged in the chamber. What’t not to like about that. While the bullet is close to the .22 long rife in bullet weight, the muzzle velocity is considerably more significant than a .22lr. I haven’t read about anyone being shot with such a high velocity bullet but I am sure it makes a significant impression upon the shootee.


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