Well I spoke to Winchester, or left them a message thinking who knows when I will get return reply. Got one in less than an hour. Returned call and discussed issue with them. Sounds like they will stand 100% behind the cases and have asked for return of both fired and unfired for testing. They indicated they will be sending along compensation so obviously I am satisfied with their customer service. Went through the reloading steps with them and I actually committed one misstep in my opinion when I was shooting. My range process is to look over each case after firing for case and primer condition. This last time, I only looked at the primers and did not really look at the case necks. If I had, I would have stopped my shooting immediately to determine cause of the split necks. Primers were fine and nicely rounded so I really didn't have any pressure concerns. No bolt lift or case stickiness either so life was grand. Basic procedure we all should be following at range when firing new step up load is examine each case neck, case body and primer for any indication of case failure and or pressure BEFORE the next round is cut loose down range. I am embarrassed that I did not follow this basic premise. I see so many folks at range just load up and cut loose without case inspection. This is a recipe for failure and could result in serious injury. You don't have to have a max load to have an Ah crap happen. In 30+ years of reloading I have had only one case head separation because I followed this simple process. And that was caused by who knows what since it was only failure in that load lot and rest were perfect. Go figure. Anyway, just thought I pass along Winchester customer service appears to be pretty good and what I think is a pretty good lesson learned even for an experienced reloader.
Muddyboots