I own a PS90 and just picked up a FiveseveN, haven't yet shot the pistol.
I like the pistol's light weight and round capacity as well as safety location just above the trigger.
As for the performance, its definitely got velocity. The 5.7 is the choice of secret service (Special rounds though), its got light recoil, albeit its pricey to shoot and not many manufacturers make it. There are some specialty manufacturers like eliteammo who provide it but right now even they are out of stock.
The 5.7 upper for an AR is pretty interesting to me, it uses the PS90/P90 magazines (up to 50 round capacity)and discharges spent casings from your lower's mag well.
In response to Myopic's statement about a potential lawsuit, I say F'em.
If the opposing attorney stated "armor piercing", I'd counter with the fact that those types of rounds are unavailable to civilians, if they say "no sporting purpose", I'd point to the box of bullets from FN that says "SS197R Sporting Cartridge",if they say "cop killer" then I'd ask the question to that "uninformed jury" to the tune of "name me a bullet that won't kill a cop or anyone else", then I'd argue to the jury what "cop killer" has to do with it if its not a police officer that was killed.
Your .45, 9mm, .40SW, is every bit as lethal as a 5.7, whether in the eyes of the law or in the heart of reasonable men. I had the duty of being on a jury in a criminal case this month which involved murder with posession of a firearm (illegal), and the DA supressed from us the fact that they also charged him with Posession of a firearm by a person prohibited, I surmise because if we had been allowed to know that charge, an astute juror who knows the law (like myself) would have known that the defendant was a person with a prior felony conviction.
If you carry legally, open or not, it doesn't and shouldn't matter what round you fire if its in defense of your life or that of your family.
Civil court is its own beast- depending on the state the jury doesn't have to be unanimous, the standards of evidence are different./ I'd still rather be judged by 12 than carried by 6 and if a 5.7 round gives me the best fighting chance of protecting me or my family, then I'll at least consider using it.
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Guns that go "Pew"= Ok.
Guns that go "Pew-Pew-Pew" = not ok.
~Joe Biden