Buffalo Bore loads their ammunition with the highest quality components available to maximize the performance of the ammunition. This ammunition is safe to use in all 357 Magnum chambered firearms with steel frames that are in proper working condition. This ammunition is new production, non-corrosive, in boxer primed, reloadable brass cases. Owner of Buffalo Bore Tim Sundles on Buffalo Bore Heavy 357 Magnum Ammunition:Our 357 mag. ammo adds more power than ever before to the 357 mag. This ammo is safe to shoot in ANY all steel 357 revolver - this includes J frames. This ammo is no harder on your gun than any other normal 357 ammo. Please don't phone us and ask if this ammo is safe in your gun. It is, providing your gun is in safe condition for use with any normal 357 ammo. We don't recommend this ammo to be fired in super light alloy revolvers as bullets may jump crimp under recoil, but the ammo itself wont hurt these super light weight revolvers. These revolvers are simply so light...