I would not necessarily expect that to be the case. Barnes also knows that just making a bigger hollow point in the end will provide adequate opening into ad copy perfect mushrooms. I have tested 30-30 TSX FN and their predecessor the X FN as well as a couple of XPB versions in .357 and .40. With the exception of the X FN 30-30 these are whopping big hollow points. The 30-30 X FN is just large compared to X bullets. The 30-30 TSX FN I tested into water down to 1100 FPS and I still got ad copy expansion. I do not remember how far down I tested the X FN. The .357 XPB I ran down to regular 38 (not 38 special) velocities. Those opened perfectly down closer to 800 FPS into water. The 30-30 TSX FN also opened perfectly and did not shed petals at slightly above 2400 FPS. The 357 XPB did not shed petals at >1700 FPS but I did not test above 1800 FPS. I think if I remember right the 125 grain .40 XPB tested OK at close to 1400, but I am not sure why that number sticks in my head, I usually wont push something that hard.
