The changeover date to non-corrosive was different for different ammo plants.
The following is something I copied from a gun discussion forum some time back. I can not vouch for it's accuracy.
Date priming changed to non-corrosive:
Frankford: FA headstamp
.30-'06 ball Oct 1951
.30 AP Oct 1951
.45 ball July 1`954
Exception: .30-'06 Match dated '53, '54 and '56 is corrosive
FCC .45 ball Nov. 1953
RA .30-'06 ball Nov 1951
" AP Sept '52
LC .30-'06 Ball June 1951
" AP April 1952
SL '06 ball May 52
AP July 52
TW '06 Ball Dec 1950
AP Feb 51
.45 ball Aug 53
WCC '06 ball June 51
.45 ball Nov 52
DAQ Canadian All Corrosive
VC Canadian All Corrosive
7.62 Nato
All was noncorrosive EXCEPT the 1956 Match which was corrosive
The following arsenals were all corrosive EW DEN DM U or UT.
