A wild guess: I have no fewer than 10,000 pieces of nickeled brass. Nothing bad has happened to my nickeled cases with the exception of tumbling. The necked pistol cases has thinned leaving the cases to take on a brass appearance. I have never had a nickeled case peal.
And then there is that thing about being a case former. I have formed nickeled cases from 30/06 to 35 Whelen and 338/06. In that effort I have had half of them split. And I have necked up 270 and 280 Remington cases to 35 Whelen and 338/06 cases. When I necked the cases up half of the cases split. But! when necking up brass cases to 35 Whelen or 338/06 cases I have not experienced split necks.
I am not talking about cases that vave been fire an unknow number of times, I am talking about new and or once fired cases.
F. Guffey