The 5.7x28 is the bottleneck cartridge FN chambers the P90 subgun and Five-seveN pistol for.
31 gr FMJ at 2329 fps from the P90, and 1971 from the pistol.
Plugging it into the Fuller Index (humor me) we get:
P90 12 inches bare gel, 9.25 cloth, 9.75 after IIA Kevlar
An estimated OSS of 70%
The pistol does 7.75, 9.0, 6.0
OSS of 60%
Great for wounding troops, not stopping BGs ASAP? Would a JHP be better? Worse?
Does not seem even close to the 223/5.56 or 224 Boz.
Mike >>>>------->
IWBA Wound Ballistics Review has the following article: "Wound profile of the 5.7x28mm FN Cartridge (SS 190) fired from the FN P90 submachine gun," by three ballistics researchers with the Royal Canadian Mounted Police.
The results: The average depth of bullet penetration in all test events (bare gelatin, gelatin covered with heavy clothing, and gelatin covered with level II soft body armor) was 10.4" with no bullet deformation and fissures created by temporary cavitation not greater than 3.75".
"The SS 190 31 grain bullet as fired through the FN P90 submachine gun has a very limited penetration profile with no bullet deformation as tested and is probably not as effective as many hollowpoint handgun ammunitions, except in
its ability to defeat soft body armor. Fackler, contradicting FN's claims, best describes the performance of the ammunition relative to the 9mm stating '...the expanded 9mm bullet strikes about three times as much tissue as the P-90 bullet at 90 degrees of yaw -- and does it throughout most of its path. Thus, the permanent cavity volume produced by the expanded 9mm bullet is many times larger than that produced by the nondeforming P-90 bullet.'"