Frankford: FA headstamp
.30-'06 ball Oct 1951

Exception: .30-'06 Match dated '53, '54 and '56 is corrosive

7.62 Nato
All was noncorrosive EXCEPT the 1956 Match which was corrosive

This may be a silly question, but why would only match ammo have corrosive primers at this late of a date? Was there an advantage to using them?
Art