I got an answer from barnes also when they became available locally that did not make alot of sense. It involved a 257 Weatherby and several whitetail deer with a 100gr X bullet at 3500+. The first deer I shot with it, behind the shoulder, broadside, I centered it perfectly, ran off without a bloodtrail at all in a thick area and was found the next day, with a pencil sized exit hole. Two more deer were shot with that gun and load that week and were nearly lost due to no blood trail to speak of, both with good hits. Barnes said that due to the hi speed that the petals must have came off, hense the small exit holes. I dont think that they opened at all. I heard a few rumors of hard bullets the first year or two. The same gun with 100gr partitions the previous year killed 5 deer instantly, but I did not get big exit holes, only around nickle size, I belive only the back half was left to exit on those due to the bullet impact and upset. I believe if the X had upset like the partition and lost it petals it would have killed as well as the partition did and the exit hole and blood trails would have not made any difference.