Tom Heller said:
"John, Blued folded mags were introduced by Mauser in mid 1937. Chrome floded tube from 1930 until mid 37 at Mauser and the blued code 122 type mags started appearing in late 1939 and changed to FXO code in 1941."
Well Tom you are really close! The blue folded tubes were first seen in the 1936 L-Block. The first Code 122 type began in the first 1940 no suffix Block. The fxo type was introduced in the early 1941 P-Block.
