Thanks for clearing that up denton.

Had two boxes of Winchester .220 Swift ammo in yellow boxes that developed the same symptoms. Got them when Old Western Scrounger had a yard sale of old stock items. Looked fine when I bought them but a couple of years later the cases were full of holes. They had been stored in a metal building and had undoubtedly been subjected to excessive heat. Glad I didn't shoot any.

One unerring mark of the love of the truth is not entertaining any proposition with greater assurance than the proofs it is built upon will warrant. John Locke, 1690