If I am not mistaken Corbon bullets come in many sizes and hardnesses. I have never used any of them as I cast my own or buy gas checked bullets from several different sources. In checking the Corbon site there are some awfully good and expierenced hunters that us them. My quess is that they know thier stuff. Certainly better than I do. I am sure that Cooper has forgoten 10 times what I ever knew about bullets and hunting the world. I would only add that if a person does not wany to use thier bullets then they should avoid them at all costs. The opposite would then hold true for those who want to use them and have had good success with them. Seem Fair?