Back in the late 70's, I bought 25 boxes(25 rds. each box) of WW Super X 00 buckshot. The shells had been in a discount store for some years. I had no use for it but they were 25 cents a box, so it seemed like a good idea at the time. By the way, it kicked real hard in my double.
After 15 or so years, the brass in many rounds began to split lengthwise. They were stored in my house, high and dry. If I remember correctly, they were not the Mark V case and had the paper base with fiber wads. As I recall, sometimes the paper bases could get moisture somehow and swell, thus expanding and perhaps causing the splitting.
