In preparation for shoot-house training, I purchased modest supply of frangible 5.56. I understand how the ammunition works in principle, metallic powder is compressed at extremely high pressures to form the bullet, and when the bullet hits a target it fragments. I have been told that, for example, a 2x4 will not cause the bullet to fragment. I was wondering what experiences people have have with frangible bullets and what will cause them to fragment/dust/vaporize as opposed to retaining their integrity. Dry wall? Sheet metal? Windshields? People?
Thanks for any information you can provide.

