Date Historic Information Serial Number Info
1954-57 The Hi-Power 9mm pistol was introduced in 1954. 70000-80,000
Accurate production figures are unavailable.
1958 In 1958 Browning kept better records of the Hi-Power pistol, so the serial number ranges are more accurate 80001-85276
1959   85268-89687
1960   89688-93027
1961   93028-109145
1962   109146-113548
1963   113549-115822
1964 In 1964 the product code for the Hi-Power was the letter "T" 115823-T136-568
1965   T136569-T146372
1966   T146373-T173285
1967   T173286-T213999
1968   T214000-T258000
1969-75 In 1969 Browning started using two digits for the date of manufacture which was followed by a four digit code that identified the type of Auto-5:
C=Hi-Power
This was then followed by the serial number beginning with 1000.
Example: 69C1000 = A 1969 Hi-Power pistol with a serial number of 1000.		 T258001-261000
C=Hi-Power
1976-1997 In 1975 Browning standardized its serial number identification which it followed until 1998.
1. Hi-Power Type 2W5=40 S&W
245=9mm
2. Date of Manufacture
is a two digit code		 Z=1
Y=2
X=3
W=4
V=5
T=6
R=7
P=8
N=9
M=0
3. Serial Number
beginning with 01001
at the start of each year.

Serial
Number Example:

245RT01001

This would be a 9mm Hi-Power pistol, manufactured in 1976 with the serial number 01001.

1998 In 1998 Browning redid the standardization of its serial number identifications to work with its new data base program, Oracle.
1. Hi-Power Type 510=Hi-Power
2. Date of Manufacture
is a two digit code		 Z=1
Y=2
X=3
W=4
V=5
T=6
R=7
P=8
N=9
M=0
3. Serial Number
beginning with 01001
at the start of each year.

Serial
Number Example:

510NN01001

This would be a 9mm Hi-Power pistol, manufactured in 1999 with the serial number 01001.

Source http://www.browning.com/