Depends on what class vest your wearing. The New vest have Titanium plates which the Special Ops use in Afgan. And according to them, it is the only vest they have that will stop this round from close range. Of course if your wearing a 1" steel plate (aviation type vest), I doubt this bullet would penetrate. But then, you would look liks Arnold S. , with a BIG S on your T-Shirt and no one would mess with you anyway
Just STAY SAFE Projekt ! Don't let'em get that close (I know, easier said than done) !
Also, the Mexicans are using these for assassinations, eliminating body guards and taking out Army Patrols with head shots. And yes, it will penetrate the Helmets with ease, from up close. But a body shot without armor is not a really good use for these bullets. They penetrate way too fast and can pass through the body without doing instant major damage unless you hit major body organs for an instant Kill (or Knock Down ability), at their speed. That's why a slower round is better for penetration AND body damage. Remember the real damage is done by this projectile AFTER it has expended most of it's energy passing through the Armor. As most know, the .45 was designed with a slow projectile, large body bullet mass and speed for KNOCK DOWN abilities on Drugged up Mora's in the Philippiens.