Pictured is an old American Body Armor ( ABA ) Threat Level II kevlar panel from one of our expired vest. It has been shot with numerous calibres to test it's effectiveness. If you look closely you can see the impacts are labeled w/calibre & bullet type. The only things that pierced it are a shank (labeled spike) and 5.56mm rifle loads (55gr W-W Ballistic-Tips). No handgun round tested came close. As you can see, most bounced off without penetrating enough to embed in the fabric. The exceptions being the .357 Magnum and .357 Sig which penetrated several layers and attached themselves to the fabric as they mushroomed. With FMJ bullets and "pointy" bullets, they would have a good chance of making it through. ( makes me think the old pointed FMJ .357 Magnum "armor piercing" load from years ago probably would defeat Level II. ) Like steel, kevlar seems most vulnerable to high velocity.
Even though the handgun bullets didnt go through, it would have been very unpleasant to endure a hit as the fabric "pooches in" when hit causing deep bruising. Thought ya'll might find this informative. Wallace