HSM Ammunition Pro Pistol .357 Magnum 158 Grain Jacketed Hollow Point Brass Cased Pistol Ammo 50 Rounds. The Pistol Pro ammo features premium jacketed Sierra bullets which is ideal for reliability and accuracy you can trust. Specifications for HSM Ammunition Pro Pistol .357 Magnum 158 Grain Jacketed Hollow Point Brass Cased Pistol Ammunition: Manufacturer: HSM Ammunition Caliber: .357 Magnum Number of Rounds: 50 Bullet Type: Jacketed Hollow Point (JHP) Bullet Weight: 158 grain Cartridge Case Material: Brass Primer Style: Centerfire HSM Ammunition 35723N: Pro Pistol .357 Magnum 158 grain Jacketed Hollow Point Brass Cased Pistol Ammo