Some things to keep in mind when considering handloading 5.7s:
- 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.
- The 5.7×28 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 5.7×28. Though the 1:9-inch twist rate of the FNH USA guns might tempt a handloader to load heavy bullets, it is highly recommend to use 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 5.7×28 is 50,040 psi.