If the two sets of numbers are in the same direction, the upper part is the factory code and the lower part is the year code.

If there is a decimal point, the decimal point is the year code.

If the last digit of a set of numbers is "1" (except those with decimal points), it represents the manufacturer.

The year code is as follows:

The year and code before 1953 are universal. For example, 1949 is1949;

Bullets from 1954 to 1960 have different years and codes, such as "54" (or a), "b", "c", "d", "Si" and "Zi", which respectively represent 1954 to 6544.

After 196 1 year, the last two digits are used for the year code.

For example, "66 1" stands for manufacturer code and "76" stands for 1976.

946 83 946 indicates the manufacturer code and 83 indicates the year. 967 1 indicates the manufacturer and 75 indicates the year.