The FN 5.7, or 5.7x28mm, cartridge has seen a resurgence in popularity since its release in 1990 and subsequent limited applications. This little cartridge is known for its armor-penetrating abilities, flat trajectory, and high velocity out of a pistol-length barrel. The FN 5.7 has better range, accuracy, and terminal performance than the 9×19 Parabellum that it was trying to replace for NATO forces once upon a time.
This cartridge is one of the most beloved — and hated — in existence today. Some experts claim it is perfect for self-defense, while others challenge those statements vehemently and regard it the same way they would a rimfire round. Despite the many arguments had over the cartridge, production continues as more and more firearms are being manufactured to fire it.
For the majority of the FN 5.7’s existence, Fabrique Nationale (FN) was the only maker of firearms chambered for this cartridge. A recent trend has brought the 5.7x28mm back in the spotlight as companies like Ruger, Kel-Tec, and Palmetto State Armory introduce pistols and pistol caliber carbines (PCCs) for the little FN 5.7, often with high capacities.
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The FN 5.7 and NATO
The development of the FN 5.7 is impossible to discuss without discussing the North Atlantic Treaty Organization, better known as NATO. In 1989, NATO was throwing around the idea of replacing the 9mm as its standard handgun and submachine gun cartridge, which would also require new firearms. It wanted a firearm and cartridge combo with better accuracy, greater range, higher capacity, equal or better terminal performance than the 9mm, and armor penetrating capabilities. This replacement cartridge was to be used in personal defense weapons (PDWs), which would replace aging submachine guns and pistols.
A year later, FN introduced the 5.7x28mm cartridge. In conjunction with the release of the cartridge, FN introduced the P90 PDW and the FN Five-seveN pistol. The bullpup P90, with its clear-plastic, top-mounted, horizontal magazine doesn’t even look like a firearm in any conventional sense and would be right at home in any sci-fi movie shooting lasers instead of bullets. In fact, it’s been used in plenty of films and TV shows since it came out.
The polymer-framed FN Five-seveN handgun was touted by FN as “the Ultimate Combat Handgun.” It held 20 rounds in the magazine and was considered ultra-high-tech at the time. The whole thing is polymer — the frame, the controls, and even the steel slide is coated in a thin polymer casing for protection against the elements.
But FN wasn’t the only company vying for the new, potentially lucrative NATO contract. Heckler & Koch developed the quite similar HK 4.6x30mm cartridge and the MP7 PDW to go with it. HK developed a handgun for the HK 4.6 as well, but it was canceled in the prototype stage.
In September 2000, NATO began testing the 5.7x28mm and HK 4.6x30mm cartridges as potential replacements for the 9mm. They concluded the trials in 2002, and the FN 5.7 proved to be “slightly superior in the field of terminal ballistics,” according to the NATO PDW Trial Report. However, the Germans objected to this ruling in favor of the 4.6x30mm, which was enough for the whole project to be halted by NATO.
Almost 20 years later, in 2021, the 5.7x28mm was officially recognized by NATO under the STANAG 4509 agreement. This wasn’t FN’s first development to get such a designation; both the 5.56 NATO and 7.62 NATO were designed by FN Herstal as well. NATO also standardized the 4.6x30mm in the same STANAG agreement, making everyone happy. In this agreement, neither the 5.7x28mm nor the 4.6x30mm replaced the 9mm as NATO’s pistol cartridge. Both were merely recognized as a standardized caliber for all NATO nations.
Both FN and HK continued to produce firearms in the above calibers throughout the delay of the NATO agreement. FN made P90s and FN Five-seveNs, eventually making them both available on the commercial market, while HK shelved its 4.6 pistol design and continued production of the MP7 submachine gun. The MP7 became extremely popular among the world’s most elite forces and is nearly impossible to obtain in the U.S. as a civilian.
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Specs & Ballistics of the FN 5.7
Unlike the majority of other cartridges in existence today, the 5.7x28mm has no parent casing. It has its own unique design and dimensions. The cartridge’s overall length is just shy of 1.6 inches, much longer than most pistol calibers. Because of this length, pistols chambered in the 5.7mm tend to have rather narrow but large grips.
The FN 5.7 uses a rebated rim design, where the rim of the casing is smaller than the case at its widest point. The rim has a diameter of 0.307 inches while the case diameter is 0.313 inches. The case diameter is 0.081 inches smaller than that of the 9×19, at 0.394 inches. This is why a pistol chambered 5.7x28mm can hold more cartridges in a similarly sized package.
The original FN 5.7 SS90 cartridge propelled a 23-grain plastic-core .22-caliber bullet at a muzzle velocity of 2,800 fps out of the P90. However, in 1993, the SS90 was discontinued and replaced with the SS190, which fired a 31-grain bullet at 2,350 fps. In today’s civilian market, weights range from 27 to 40 grains. The 27-grain bullet that FN uses for its factory ammo is lead-free and has a brass jacket with an aluminum core. FN’s 40-grain polymer tip option uses a Hornady V-Max bullet and is loaded in the U.S. by the Federal Cartridge Company.
The flat trajectory of the little 5.7mm blows the 9mm out of the water. With a 50-yard zero at 200 yards, a 9mm will drop nearly 30 inches, whereas a 5.7x28mm drops only 2.5 inches. These numbers are out of a P90 PDW and PCC. While 200 yards seems a little far for both of them, FN claims the 5.7 remains effective at that range.
Compared to the 9mm, the 5.7x28mm has significantly less felt recoil. FN claims the felt recoil reduction is around 30% compared to the 9mm. This helps keep the gun on target for faster follow-up shots and makes it easier to shoot.
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The 5.7x28mm for Self Defense
The 5.7x28mm is one of the most controversial self-defense calibers on the market today. This controversy isn’t just between firearms owners arguing its lethality; the anti-gun crowd has made repeated attempts to get it banned in the U.S. Initially, FN only sold the FN Five-seveN pistol to law enforcement and the military. In 2004, the company decided to take it to the civilian market, causing an outcry from the anti-gunners.
“The Brady Campaign took notice of the weapon and opposed its importation into the United States on the grounds that the 5.7mm round penetrated Level IIA Kevlar vests and was therefore not a gun that belonged in the hands of civilians,” wrote Will Ellis in Gun News Daily.
Today it is completely legal to own. However, FN decided not to offer armor-piercing ammunition to the civilian market. For gun owners, it seems that people either love or hate it. FN advertises it as a suitable tool for home defense and personal protection, but some disagree, comparing it to a 22-magnum rimfire.
FN borrowed the light and fast bullet idea from the 5.56 NATO. But despite being nearly twice as fast as the 9mm, the 5.7x28mm hits with about 66% of the energy. Most self-defense situations are at close ranges, negating the argument of a flatter trajectory at distance. Lastly, the current 5.7 pistol options on the market are all full-sized firearms, limiting the conceal carry options for most users.
The little 5.7 cartridge does have some features that lend it to being a great option for self-defense. First and foremost is magazine capacity. Handguns chambered in the 5.7x28mm typically hold 20 rounds or more in a flush mag, and the low recoil lends itself to faster follow-up shots. The counterargument to the energy debate is that of shock. Think .220 Swift or .22-250 in the hunting world. Small bullets moving very fast tend to create large wound cavities as they pass through a body that upset the nervous system. As with most caliber debates, choosing the right bullet is far more important than the right caliber.
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Some Current Production 5.7x28mm Firearms
The FN P90 holds the title of being the first firearm chambered in 5.7x28mm. Designed in the late 1980s to replace the dating submachine guns of the era, this PDW is smaller than the famed MP5 and has a 50-round capacity. Unique to this firearm is the strange top-mounted magazine that sits flush with the gun and holds the cartridges horizontally or 90 degrees off the bore. While not adopted on a large scale, it has been adopted by more than 40 countries and is used by many defense and security protection details.
Unfortunately, the genuine P90 is only available for military and law enforcement sales, since it has that full-auto fun switch. FN sells a carbine version of the PS90 that gets transferred as a long gun, which is nearly identical to the P90, except it has a 16-inch barrel and no full-auto sear or selector. A PS90 can, of course, be SBR’d later on to create a sort of semi-auto-only P90.
The FN Five-seveN was the original pistol made for the 5.7x28mm. It was ahead of its time and is still available today. The pistol’s frame is made of polymer and offers a checkered grip and MIL-STD-1913 accessory rail. The improved controls, such as the ambidextrous safety and reversible mag release, make operation easy for both right- and left-handed shooters.
The Five-seveN utilizes a chrome-lined, cold-hammer-forged barrel that is a tack driver. It has a one-piece steel slide, internal hammer, and smooth trigger; the standard magazine holds 20 rounds. The FN Five-seveN has decades of trusted use around the globe. This is the most expensive option out of the pistols listed.
Ruger earned the American Riflemans’ “Handgun of the Year” award in 2021 with the introduction of the Ruger-5.7 Pistol. This polymer-framed pistol has a textured grip, ambidextrous thumb safety, and trigger blade safety. The internal hammer helps produce a short and smooth trigger pull. The slide is through-hardened billet steel that comes drilled and tapped for optics mounting options. The magazine holds 20 rounds and is made of steel.
The Ruger LC Carbine is the rifle counterpart to the Ruger 5.7, sharing similar ergonomics and the same magazines. The carbine comes in under six pounds and includes a fluted and 1/2”-28 threaded barrel, folding adjustable stock, ambidextrous safety, and a reversible charging handle. The aluminum handguard has a Picatinny rail running down the top and M-Lok-compatible slots on the sides and bottom.
The PSA Rock is a great entry-level-priced 5.7mm pistol. It is a full-sized, polymer-framed pistol that holds 23 rounds in a standard magazine. It is a single-action, striker-fired design that produces a 4.5-pound trigger pull. The barrel is fluted carbon steel and works on a delayed blowback principle. This pistol is an excellent option for someone who wants to add a 5.7mm to their safe.
The Kel-Tec P50 is a unique pistol that would look right at home in any action movie tucked under someone’s suit jacket in a shoulder sling. Staying true to Kel-Tec fashion, the P50 is different from everything else on the market. It has an overall length of 15 inches and uses existing 50-round P90 mags. Kel-Tec advertises this 5.7x28mm pistol as “Unique, Adaptable, Retro.”
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The Cost of the FN 5.7
When entering the 5.7x28mm world, you must consider ammunition cost. Current inflated ammunition market conditions put the 5.7 anywhere from $0.84 to $1.30 per round. Compare that to the 9mm, in which a box of range ammo can be found for about $0.30 a round, and you’ll see why some are apprehensive.
However, there is light at the end of the tunnel here. Currently, only Federal and FN market 5.7x28mm ammunition to civilians in the U.S., and because of the fragile neck of the casing, it’s notoriously difficult to impossible to reload. But, the increased popularity and available firearm options on the market will hopefully bring some additional ammunition manufacturers into the game.
Theoretically, the more popular this cartridge becomes, the more ammo will be produced and the less expensive it will be. But the 5.7 would have to get pretty popular for ammo companies to divert resources away from producing 9mm, .223, or other highly popular cartridges.
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