Buffalo Bore Ammunition Heavy 357 Mag 125 Gr Jacketed Hollow Point JHP. ammo adds more power than ever before to the 357 mag. This ammo is safe to shoot in ANY all-steel 357 revolver including J frames. This ammo is no harder on your gun than any other normal 357 ammo. NOTE: This ammo is not recommended to be fired in super light alloy revolvers. Specifications for Buffalo Bore Ammunition 19D/20 Heavy 357 Mag 125 Gr Jacketed Hollow Point (JHP): Manufacturer: Buffalo Bore Ammunition Caliber: .357 Magnum Number of Rounds: 20 Bullet Type: Jacketed Hollow Point (JHP) Bullet Weight: 125 grain Cartridge Case Material: Brass Muzzle Velocity: 1700 ft/s Application: Protection Primer Style: Centerfire