My experiences were early on in the Balistic tip craze. I was shooting PD's at the time and loved the 40 gr BTs but noticed that the bullet seemed to be inconsistent in the performance. One minute they would blow a PD to pieces on the next shot at an almost identical target they would simply punch a 224 hole. I don't know if this was an oddball batch of bullets or not but some bullets seemed MUCH more explosive than others.
Well anyways, I still had some available when Coyote hunting so I used them on coyotes. Most were DOA hits. But I had one come in to about 30 yards, give me a perfect broadside shot, the shot hit between the back of the ribs and the elbow, a perfect hit really, the hit was easy to hear, the dog went right down, popped right back up and started to run in 30 yard circles, I could see the hole, the blood was spraying everywhere. After about 5 lapps it looked like he was not going to stop so I lined up for another shot but he dropped stone cold dead. A close examination of this coyote showed the entrance hole was about 3" in diameter, the ribs were exposed but not broken, there was a small hole entering the body cavity which turned out to be the bullets base and that is what killed him, there was no exit wound (I hate blood and gore pictures but I took a picture of this coyote). By all rights this coyote should never been able to take a single step after the shot. If he had not run in circles I'm sure that he would have been lost, as it was he ran a long ways before dropping dead. This expereince turned me away from using the 40's for coyotes. But I've often wondered if I got a bad batch of bullets some hard and some ready to fragment at the slightest provocation. Like I said this was in the very beginning of the Nosler BT 40's life. I'd read Steve Timm's first article on the 40gr BT and haunted the suppliers until they were generally available and this bullet came from that first batch of bullets.