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Pros of Nickle Cases
Corrosion Resistance

One of the biggest benefits of nickel cases is their inherent corrosion resistance. Nickle plated brass casings can be handled consistently or stored on a leather gun belt for extended periods of time and show zero signs of tarnish.
Lower Coefficient of Friction

Another benefit of nickel cases is that they have a higher surface lubricity than standard brass. This means that nickel plated brass cases will generally feel slicker, have improved feeding into the chamber for a semi-auto, and provide easier case extraction from a revolver like a 357 Magnum. This is one reason why many ammo manufacturers have started offering defense loads in nickel plated cases, as they are generally more reliable.