I've always considered it to be about like a 22 mag.
Here is what Wik has for info. Sounds like performance varies a bit.
Quote:
"Some military and police personnel view the 5.7x28 mm SS190 skeptically, although it is touted as a solution to defeating modern body armor. Many regard the SS190 as having insufficient "stopping power" for law enforcement use and this topic has seen much debate. A brief controversy ensued in the United States in 2004 when it was claimed by the Brady Campaign that the civilian-legal SS192 cartridges are able to pierce Level IIA body armor when fired from the Five-seveN pistol. All civilian-legal game hunting cartridges, and even several pistol cartridges, are capable of such penetration. The ability of SS192 to pierce body armor as claimed by the Brady Campaign was not confirmed with facts or data by any authoritative agencies or sources. The ammunition was not restricted for civilian sales, since it is not legally recognized as armor piercing by the BATFE. Nonetheless, FN chose to withdraw the SS192 from the market and replace it with the SS196SR. The SS196SR's performance against armor is diminished due to a heavier varmint bullet (leading to lower muzzle velocity) and a polycarbonate tip that promotes expansion and fragmentation upon impact. The performance of such cartridges are similar to the .22 WMR (.22 Magnum)."
One of these would be a better choice. /ubbthreads/images/graemlins/grin.gif
