Sometimes we get the funniest questions!!! This has been discussed at length in several reloading manuals over the years.
Boss Hoss - sorry about posting such a silly question
For something that's been written about for so many years, there's still a lot of rumor, conjecture, and speculation. ...and, flat out wrong thinking
Since I first posted this, I've seen 6-10 articles/books/studies referenced in many various other threads. There's one common theme in that no bullet is immune to deflection. But, most of these studies are not scientifically nor statistically valid studies in terms of comparing bullets and they often draw different even conflicting conclusions about which cartridge/bullet is best.
While deflection has been the focus of much of the discussion here, expansion/fragmentation is something I was/am curious about as pointed out by elkaholic.
Incidentally, Barnes was quick to respond to my questions about expansion and what it takes to trigger it in their bullets. But, Berger has been dead silent since I asked them. I guess they're out shooting rather than watching email.
It is a silly question like asking how many grains of RL22 does it take to ruin your action. The short answer being "don't go there."
Nonetheless, it's still something I'm interested in knowing more about.