About 1930 and again after 1945 the date markings af Mannlicher-Schoenauers were changed. Also, the serial numbers are unusable for dating, as each model had it's own serial number range. Some examples:
M1924 in .30-06, #299 date 1618.27 = 1927
M1925 in 8x60 Magnum, #3233 date 34. = 1934
M1903 in 6.5x54, #23979 date 36. = 1936
M1910 in 9.5x57, #11400 date 37. = 1937
M1950 in 7x57, #3092 date 51 = 1951
"M1950" (marked such, but a post-1952 magnum action) in 6.5x68, #22638 date 57 = 1957.

Note, up to about 1930 there was a dot in front of the year digits, after the proofhouse ledger number. After 1930 no ledger number, dot after the year. 1950 on year only, without a dot.