Not really armor penetrating as much as have a tendency to over penetrate. It is a very small bullet with a lot of powder behind it, so it has a lot of force that would go through armor but wouldn't be great for stopping power as it would just go in and out of the target, even with armor. I recall hearing about a call where a Five Seven misfired at a range, went through the wall, through a guys shoulder, through the next wall and was never found. It is a really nice round for small guns like the P90 where it would be used for defense against targets with body armor but again I don't see a normal person having one, especially a full auto one with a short barrel where you can get the full potential out of it. As a special weapon for secret service against armored opponents it would be a nice rework to deal less damage but ignore armor, (even though every bit of mass it goes though would slow it and be damaged) I am kinda on the fence about it.. I do agree new weapons would be nice, but I don't want it to be the main focus as it was in OCRP when it was popular.