5.7x28mm Ammo

What is 5.7x28mm?

5.7x28mm was developed by FN Herstal in the late 1980s as part of a NATO program to replace 9mm pistols and SMGs with a lighter, higher-velocity round that could defeat soft body armor. The military loading (SS190) uses an armor-piercing steel-core bullet and is not commercially available to civilians — a fact that matters for understanding what civilian 5.7 actually does.

The civilian loads sold by FN and other manufacturers use standard lead-core projectiles and produce no meaningful armor-penetrating capability. The cartridge’s small diameter (.224”) and high velocity produce low recoil, flat trajectory, and high magazine capacity.

For years, 5.7x28mm was exclusively the FN Five-seveN pistol and PS90 carbine — niche, expensive, and hard to feed. The Ruger-57 (2019) changed that by offering a mainstream platform at a reasonable price. Smith & Wesson followed with the M&P 5.7, and CMMG built an AR-style rifle version. The cartridge went from curiosity to a legitimate market segment.

The body armor claim: what civilians actually get

The military SS190 round — steel-penetrator core, available only to military/LE — defeats NIJ Level IIIA soft body armor at close range. This is true and well-documented.

The civilian SS197SR and similar loads — lead or polymer core, no steel penetrator — do not penetrate soft body armor in any meaningful way. Testing shows they perform similarly to 9mm against armor. The armor-defeating capability exists in the restricted ammunition, not in the cartridge itself.

Terminal ballistics: the honest gel data

From a 4.8” barrel (Ruger-57), FBI protocol (10% gel, 4 denim):

Meets FBI minimum (12”) for penetration with defensive loads. Expanded diameter (~0.43–0.45”) is smaller than top 9mm loads (~0.60–0.72”). The V-MAX is a varmint/frangible bullet that fragments rather than expands — not ideal for defensive use.

5.7 defensive loads work, but they don’t outperform modern 9mm hollow points. The case for 5.7 in defensive use is about the platform (20-round capacity, very low recoil) rather than ballistic superiority.

5.7x28mm vs. 9mm: when to choose each

9mm wins on terminal performance, cost, and platform selection. 5.7 wins on capacity and recoil. The right answer depends on what you’re optimizing for.

Carbine use: the PS90 advantage

The PS90 (civilian version of the military P90) is where 5.7x28mm makes more sense as a ballistic choice. From the 16” PS90 barrel:

• Velocity jumps ~400–500 fps over pistol barrels
• 40gr V-MAX at ~2,300 fps from a rifle barrel fragments reliably on varmints and is effective at 150+ yards
• The bullpup design keeps the package compact despite the rifle barrel

For varmint hunting, home defense from a compact rifle platform, or suppressed use (5.7x28mm cans are small and quiet), the PS90 is a serious tool.

Who 5.7x28mm actually makes sense for

A few situations where it’s the right call:

High-capacity home defense pistol. 20–22 rounds in a handgun is genuinely useful. Recoil is minimal — this matters for smaller-framed shooters or anyone who has trouble managing standard semi-auto recoil. The S&W M&P 5.7 at 22+1 is competitive on capacity alone, and if the mild recoil means you practice more, the tradeoff is worth considering.

PS90 suppressed build. The PS90 with a quality suppressor is one of the quietest and most compact centerfire setups available. The 16” barrel recovers the velocity that short pistol barrels lose, and the bullpup format keeps the overall length manageable. For a bedside or truck rifle where compactness matters, this is a legitimate setup.

Existing platform owner. If you already own a Ruger-57 and are comfortable with it, the ammo selection has improved enough since 2019 that you’re not carrying a second-class defensive load anymore. Speer Gold Dot 40gr meets FBI minimum penetration. Run it with confidence.

Where it doesn’t make sense: as a primary carry gun when 9mm is manageable. Practice ammo runs $0.50–0.65/round vs. $0.18–0.25/round for 9mm. At 200 rounds a month, you’re paying an extra $600–900/year just to practice. That’s real money for marginal capacity benefits over a modern high-cap 9mm.

Brand guide

Speer Gold Dot 40gr — the defensive standard, most consistent gel performance among civilian 5.7 loads. ~$0.65–0.90/rd.

Hornady Critical Defense 40gr FTX — polymer tip for reliable expansion, good penetration. ~$0.65–0.90/rd.

FN SS197SR 40gr V-MAX — the original FN commercial load. Fragmenting design, good for varmints, not ideal for defensive use. ~$0.55–0.80/rd.

Federal American Eagle 40gr FMJ — range standard. Clean, reliable. ~$0.45–0.65/rd.

Federal Personal Defense 40gr HP — Federal’s defensive load, consistent performance. ~$0.65–0.90/rd.

Fiocchi 40gr FMJ — European manufacture, competitive pricing for practice. ~$0.42–0.60/rd.

Price guide (2025–2026)

5.7x28mm practice runs roughly 2.5–3x the cost of 9mm. A 1,000-round practice session costs roughly the same as a new budget 9mm pistol. Plan your training budget accordingly.

Firearms chambered in 5.7x28mm

Pistols:

• FN Five-seveN — the original; DA/SA trigger, 20+1 capacity; expensive (~$1,400+)
• Ruger-57 — the accessible option; ~$700; excellent value, SA trigger, 20+1
• Smith & Wesson M&P 5.7 — polymer striker-fired, 22+1 capacity, optic-ready
• Diamondback DBX57 — compact pistol-caliber carbine hybrid

Rifle/carbine:

• FN PS90 (civilian P90) — 16” barrel, 50-round top-loading magazine, bullpup
• CMMG Banshee/Resolute 5.7x28mm — AR-style, multiple barrel lengths
• Palmetto State Armory Rock 5.7 — budget AR-style option