Valid question, I asked him the same thing. Turns out he was using FMJ rounds. Ironically, one of his tenants (he owns a group of rentals) was the ER nurse who treated the "gangsta". After all came full circle, his tenant told him they would've let him die on the table if they would've known, but after he was dropped off at the hospital the cops told him the "gangsta" was a drive-by victim. After all was said and done, he had to identify the "gangsta". This was a task in itself, since they couldn't put a hat on him that would stay, since the back of his skull was gone, so a line up was out of the question. He ended up identifying him from old pictures that were taken years before. He still believes in the .45, but now owns a Glock 21 and uses quality hollow-points. I asked him why not FMJ since some didn't penetrate the bed of his truck and his answer was simple, use quality hollow-points and they should, if they hit a barrier, penetrate. To this day, I use Winchester PDX1's, since they are designed not to expand if a barrier is hit.
This is not a story of uncle's wife's cousin who know a guy......this happened. You can believe it or not, I don't really care. OP asked for a actual CCW contact survival experience and that's what I a gave. "Bob" is a family friend (more than that his a fellow Marine) and I will not betray his trust by giving names or locations.
I choose to learn from other peoples "mistakes" or lessons learned. Take it or leave it, your choice. I learned and attempted to share the lesson.
Side note: a human skull is nothing like a watermelon!!! That looks good on TV, that's about it. I can smash a watermelon with my bare hands easily, try that with a human skull using the same force. We humans are are lot more resilient that watermelons.