Reports of no expansion are very rare but to say that it has never been reported isn't factual. It is very important to us that we get the specifics of this situation. I suggest that either you or the hunter you mention gets in touch with us directly so we can learn all we can. You can email me at firstname.lastname@example.org
In the few reports we've received, we have been unable to get to the root cause of this result. This is primarily due to the infrequency of the occurances. Also, we have been unable to duplicate this result in our testing. Having said that I will offer some thoughts on potential causes.
Using Hunting bullets rather than Target or Tactical bullets (we don't make a 168 gr Tactical so that doesn't apply in this situation) is important. The thicker jacket used in the Target and Tactical bullets has proven to open up and fragment less than the hunting jackets.
Impact velocity is important. The lower the impact velocity, the less expansion and fragmentation will occur. Our Hunting bullets have been shown to open up at 1,800 fps which is low compared to many other options. The fact that you mentioned the range was 200 yards suggests that the impact velocity should have been high enough.
Trimming and repointing Berger Hunting bullets is strongly discouraged. You didn't mention that this was done but I wanted to mention it for others reading this thread. The size of the hollow point affects penetration and expansion. If the tip is repointed to be very tight, it can prevent or significantly reduce expansion.
I look forward to hearing from you so we can do all we can work toward eliminating this from ever happening.