January 04, 2019
By Greg Rodriguez
The 5.7x28mm cartridge was developed by FN for use in a new line of carbines, pistols, and submachine guns. FN was looking for a cartridge that offered low recoil and the high velocity necessary to defeat body armor--with a special armor-piercing projectile--or deliver one-shot stops with the appropriate bullet. This rimless, bottlenecked cartridge fit the bill, and with the exception of the steel-penetrator-tipped/aluminum-core AP round, it's now commonplace on the market.
Despite its 5.7 designation, it actually utilizes .224 bullets; 5.7 is the groove diameter. Some have compared the 5.7x28mm to the .22 Hornet. However, even from a carbine-length barrel, it does not quite meet Hornet velocities with equal bullet weights. Still, it is a wonderful little cartridge that is hell on varmints and a blast to shoot.
- Case: FN
- Case Capacity: 14 grains of water
- Primer: Federal Small Rifle
- Case Length: 1.135 inches
- OAL: 1.594 inches
Favorite 5.7x28mm Handloads
|Bullet||Starting Load Powder||Starting Load Grains||Velocity* (fps)||Max Load Grains||Velocity* (fps)||Cart. Length (in.)||Comment|
| || || || || || || || |
|Hornady 35-gr. V-Max||True Blue||5.3||1522||5.9||1738||1.525||Accurate load|
|Hornady 35-gr. V-Max||AA No.7||6.7||1663||7.5||1791||1.525||All-purpose load|
|Sierra 40-gr. SP||True Blue||5.2||1587||5.8||1779||1.525||Great jackrabbit load|
|Sierra 40-gr. SP||AA No.7||6.3||1549||7.0||1711||1.525||PS90 loved it with 7.0 grs.|
|* 5-inch barrel|
I only started loading the 5.7 for this article, so I do not have a lengthy list of handloads. So far, I've found reloading the 5.7x28mm to be fairly straightforward, so long as the handloader is meticulous in every operation of the loading process. There are a few things to keep in mind:
- Using reloaded ammunition in PS90 and Five-seveN firearms voids any warranty and any liability of FNH USA. By choosing to reload, you accept full responsibility.
- Because of its tiny case capacity, start at the listed minimums and work your way up in 0.1-grain increments.
- Published load data varies greatly, so err on the conservative side. The min. and max. loads in the Western Powders manual are significantly higher than those listed in the new Lyman Reloading Handbook 49th Edition, which is what I used.
- The 5.7x28 is very sensitive; adhere strictly to the loading data and COL guidelines.
- Stick with flatbase bullets and Small Rifle primers. If you use Small Pistol primers, expect decreased performance.
- Excessive muzzle blast and flash are to be expected with this cartridge.
- FN- and Fiocchi-made ammunition both employ military-style, staked-in primers. You must ream the staking residue from the primer pocket before reloading.
- Beware of hotrodding the 5.7x28. Though the 1:9-inch twist rate of the FNH USA guns might tempt a handloader to load heavy bullets, I highly recommend projectiles of 40 grains or less. Too-high pressures can be a real safety concern with the straight blowback PS90 and the delayed-blowback Five-seveN pistol.
- The maximum average pressure (MAP) for the 5.7x28 is 50,040 psi.