5.7x28 vs 9mm: what the cartridge really is and where it wins

Key points: 5 7x28 vs 9mm

• FN designed 5.7x28 in 1990 as a 9mm NATO replacement for a PDW and a pistol; the hosts land on pistol cartridge rather than rifle round, noting the necked case shape it shares with 357 SIG and 7.62x25 Tokarev.
• NATO testing in 2002 and 2003 favored 5.7 over HK's competing 4.6x30 in the MP7, but Germany rejected the findings and NATO did not formally list the round as a standard option until 2021 — by which point more than 40 countries had already adopted a 5.7 firearm.
• The armor-defeating reputation belongs to the original specification ammunition out of the P90's 10.5-inch barrel, not the commercial sporting ammunition civilians can buy.
• The performance trade is velocity for energy: roughly 1,800 to 1,900 fps at the muzzle buys a flatter trajectory and lighter recoil, but 9mm carries more energy at 100 yards than 5.7 makes at the muzzle, and 5.7 sheds about 500 fps over that distance against roughly 100 for 9mm.
• Capacity is the practical argument — 20 rounds in an FN Five-seven, 50 in a P90 magazine that weighs about the same as a loaded AR-15 magazine — with lighter recoil supporting faster follow-up shots.
• The PS90 is genuinely ambidextrous: safety ahead of the trigger workable from either side, charging handles on both sides, magazine release at the rear, three iron sights (left and right notch-and-blade plus a center peep), and downward ejection — which the AR57 upper keeps by turning the magwell into the ejection port.
• Support is broad enough to argue the round is here to stay: FN, Ruger, Smith & Wesson, CMMG, Kel-Tec and Masterpiece Arms all chamber it, and volume production from loaders like American Eagle has pulled prices down, though 9mm still wins on cost.

About this Gun Review video

5.7x28 vs 9mm, argued from design intent outward: Classic Firearms hosts Matt and Jason make the case that 5.7x28 is a pistol cartridge rather than a rifle round, since necked pistol cases like 357 SIG and 7.62x25 Tokarev long predate it. They cover FN's 1990 brief to replace 9mm NATO, the NATO trials against HK's 4.6x30, the velocity-for-energy trade against 9mm at 100 yards, 20-round Five-seven and 50-round P90 capacity, the fully ambidextrous PS90, and how many makers now chamber the round.

Transcript: 5 7x28 vs