5.7x28 is a legitimate but specialized carry choice. From the FN Five-seveN MRD it delivers 20+1 rounds with recoil closer to a .22 Magnum than a 9mm, which is a real advantage for recoil-sensitive shooters. Its light bullet gives up terminal mass to 9mm, ammunition is costly and scarce, and holsters are limited. If those constraints fit your life, it works. For most carriers, 9mm remains the rational default.
What 5.7x28 Is
FN Herstal developed 5.7x28mm in the late 1980s for the P90 personal defense weapon and the Five-seveN pistol, as a NATO-oriented replacement for 9mm that could defeat soft body armor with its armor-piercing military loading. The civilian loads sold in the U.S. are not armor-piercing; they're light bullets, typically 27 to 40 grains, at high pistol velocity. FN's SS197SR sporting load, a 40-grain polymer-tipped bullet, is the reference commercial round and FN publishes its velocity from the Five-seveN in the high 1,600s of feet per second. The cartridge went mainstream on the civilian side after Ruger, Kel-Tec, and others introduced pistols in it, and Kel-Tec's PR57 is covered in our PR57 vs P365 comparison.
| Factor | 5.7x28 (Five-seveN MRD) | 9mm (typical compact) |
|---|---|---|
| Capacity | 20+1 | 10 to 17+1 |
| Bullet weight | About 27 to 40 gr | 115 to 147 gr |
| Recoil | Very low | Moderate |
| Trajectory | Very flat | Adequate |
| Ammo availability | Limited; costly | Everywhere |
| Holster market | Small | Enormous |
What the Sourced Data Says
Independent gel testing of commercial 5.7x28 loads, including the widely cited tests published by Lucky Gunner and others, generally shows adequate penetration with expanding or fragmenting light bullets and narrower permanent wound channels than 9mm hollow points, which is what physics predicts from a 40-grain projectile. Proponents point to the velocity, the flat trajectory, and the capacity; skeptics point to the mass. Neither side has data showing it's ineffective; the honest summary is that it works with less margin than 9mm, and that the margin matters more with poor shot placement. We don't invent gel numbers here; read the published tests for the specific load you'd carry.
Why Someone Chooses It
- Recoil. The Five-seveN's recoil is remarkably light for a full-size pistol. For a shooter with arthritis, a wrist injury, or a small frame who can't run a 9mm well, that's not a novelty; it's the reason they can carry at all.
- Capacity. Twenty-one rounds in a pistol that weighs less than most 17-round 9mms.
- Trajectory. The cartridge shoots flat to distances where pistol fights don't happen. It's a nice-to-have.
Why Most People Shouldn't
- Ammunition. 5.7x28 costs several times what 9mm does and is stocked far less widely. At the time of writing, Ammunition Depot's catalog pull had no dedicated 5.7x28 product page, which tells you something. Practice volume suffers.
- Holsters. The Five-seveN's shape is unusual and its holster market is a fraction of a Glock's. Plan to order rather than browse.
- Size. It's a full-size pistol with a long grip. It conceals like a Glock 17, not like a P365.
The Pistol: FN Five-seveN MRD
FN Five-seveN MRD 5.7x28mm, flat dark earth
Optics-ready5.7x28 · 4.8 in · 20+1
The MRD is the current Five-seveN with an optics-ready slide and a multi-plate mounting system. Full-size, very light, with FN's ambidextrous controls. This is the reference 5.7 pistol, and the one the terminal data above is measured from.
FN Five-seveN MRD 5.7x28mm, black
Same pistol5.7x28 · 4.8 in · 20+1
Identical specification in black. Choose by finish; the rest is the same gun.
Mounting a Dot
The MRD ships with a plate system intended to cover common optic footprints. A Holosun 507C X2, which uses the Trijicon RMR footprint, is a natural match for a full-size slide if the RMR plate is included in the box for the version you buy; confirm on FN's specification for the current MRD before ordering the optic. The red-dot carry guns guide covers plates and footprints.
The Bottom Line
If recoil is what stands between you and carrying a pistol competently, the Five-seveN is one of the few full-size guns that removes the problem, and its capacity is a real asset. If you can shoot a 9mm well, the 9mm defensive ammo guide and the full-size handguns guide cover a cartridge with more mass, more choice, and less cost. Both positions are defensible; only one is the default.
Key Takeaways
- 5.7x28 delivers 20+1 rounds with very low recoil and a flat trajectory from the FN Five-seveN MRD.
- Published gel tests show adequate penetration and narrower wound channels than 9mm; it works with less margin.
- Ammunition is costly and scarce, holsters are limited, and the pistol is full-size.
- A rational choice for recoil-limited shooters; 9mm remains the default for everyone else.
Frequently Asked Questions
Is 5.7x28 a good self-defense cartridge?
It's adequate, with published testing showing acceptable penetration and smaller wound channels than 9mm. Its advantages are capacity and very low recoil; its disadvantages are bullet mass, ammunition cost, and availability.
Is civilian 5.7x28 armor-piercing?
No. The armor-piercing military loading is restricted. Commercial loads sold to civilians are conventional light bullets.
How much does the Five-seveN recoil?
Very little for a full-size pistol; closer to a .22 Magnum than a 9mm. That is the cartridge's strongest argument for recoil-sensitive shooters.
Does the Five-seveN MRD take a red dot?
Yes. The MRD slide uses a plate system for common footprints. Confirm which plates ship with the current version before buying an optic.