The Nickel-plated brass is harder than standard brass is has been shown to withstand C.U.P. pressure as much as 20% higher than standard brass. I take it that this is being fired in a pistol, and on the third loading of the brass, the brass failed? Is this correct ?? If you are loading near the top of the pressure limits with brass, then switched to a Nickel-plated brass your Pistol may need a heaver recoil spring or the guns original spring is week. The nickel may not be gripping the walls of the chamber and prematurity be opening.
What gun is it in and what load are you using. that would be the next question. It would be safe to say you need to check things out before you proceed any further shooting of this gun...
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