It's kind of a spin off from the hevi shot. It's supposed to be better though. I don't know why a company has to change a good thing. I used the hevi shot mags. They patterned the best out of my gun, and now they don't make them any more. I do still have two boxes of them though. The HD is supposed to be new and improved, and faster. They guarantee all pellets to be uniform to improve velocity, more knock down power and a longer maximum range. On paper, it sounds like an awesome load. I will try them out and let every one know how they did. I may try to find some this weekend.