My experience is anecdotal as well. I have found critters unimpressed with double lung shots after being hit with 168 grain .308 Triple Shoks impacting at 2600-2700 fps. My last double lung shot was on a doe antelope that had pieces of lung blown out the exit hole, and it still ran over a berm like nothing had happened. (It went less than 100 yards.) I would not discount hard cast on this basis alone.
Thanks for sharing your experience Cheyenne. That's kind of surprising to me.
Every 2x-lung rifle shot I have ever seen was almost instantly fatal, but that could be a coincidence.
For example, my boy's first deer died where he stood:
This guy went down immediately.