You will have to call Browning or visit their website with the sn.
The 2 letters found in your serial number(MZ) indicate that your Browning safari was made in the year 2001.
2000
1969
1969
1969
1994
With the 5L prefix to your serial number indicates that your Browning model safari bolt action rifle was produced by FN of belguim for Browning in 1965.
The answer to the question is "1962". That is the year represented by the 2. The L is the code letter for Safari Grade and 10285 is the rifle's serial number.
YOu will have to call Browning.
1996
Go to Proofhouse.com and search the Browning serial number tables.
With the serial number that you supplied,your Browning Safari bolt action rifle was produced by FN of Belguim for Browning in the year 1963.