>>64110915
>>64110934
5.7 can pen the crisat target (1.6mm titanium backed by 20 layers of kevlar) at 205 meters exactly.
https://en.wikipedia.org/wiki/Collaborative_Research_into_Small_Arms_Technology
https://web.archive.org/web/20110707175011/http://www.asianmilitaryreview.com/upload/200712031747321.pdf

The crisat target is supposed to represent the soviet 6B2 body armor and some lighter version of the 6B3/6B5 armor that have similar protection to the 6B2. So the poor nato truck driver equiped with a P90 should be effective against soviet paratroopers with lighter armor models up to 200 meters.

https://www.youtube.com/watch?v=MbPT9z_RzYA

Main problem is that it fails hard against rifle resistant 6B3 equiped with 6.5mm plates. It will fail even harder against any soviet armor rocking the ceramic carbid core plates.

https://www.youtube.com/watch?v=Py9MJUmdQ4o
According to henry, soviet paratroopers actually dropped slick, having the armor be inside the air dropped apc/ifv and then equiping it on the ground after landing. And IIRC in the soldier of fortune magazine which did some test in 1984 on the early 6B2 armor, can be penetrated by steel core 9mm fired from submachine guns at very close range anyway. This makes the whole "kill paratroopers wearing armor with this new caliber" a very specific scenario that is somewhat unlikely to justify a whole new weapon system just for that scenario. The soviet union also died after the P90 program was finished.

In the context of home defence. The P90 should kill any burglar that is smart enough to wear soft armor assuming you are not firing subsonic rounds.