I had a batch of Winchester 30-06 that splits necks on the third reload. I am still using Remington brass that have 6 loaded rounds gone through. I just found this weekend one Remington factory round split from the first shot. I am using 30-30 Winchesters that have 8 loaded cycles and was worried I would have problem when I purchased them back a year ago.
Must be bad batch. I am thinking about annealing my brass in the future. It's hard to say.