I see where ATG currently has both Hydra-Shok and a cheaper ammo called "Hi-Shok". I own Hydra-Shok but this is the first I've seen Hi-Shok. The description on ATG's website makes it sound like an older gen ammo. There is no info on this cartridge on Federal's website. Can someone educate me on the difference? Is Hi-Shok worth buying?