Buy Hornady Custom Ammunition 357 Magnum 158 Grain XTP Jacketed Hollow Point Box of 25 Online. Hornady custom-grade ammunition from the factory. Hornady Custom ammunition is manufactured to give shooters and hunters the advantage of hand-loaded accuracy in a factory load. This ammunition is new production, non-corrosive, in boxer primed, reloadable brass cases. One of the great things about the XTP bullet is reliable performance, it features controlled expansion where six serrations divide the bullet into six symmetrical sections. These sections weaken the jacket to allow controlled expansion at low velocities and ensures fragmentation does not occur at high velocities. Each XTP Bullet has a swaged core and drawn copper jacket to ensure uniform expansion and in-flight stability.