3spop,
What year is your H&R 999? If the serial number is prefixed with an alpha character, the year of manufacture can be determined by using the following;
A = 1940
B = 1941
C = 1942
and so on... (the letters "O" & "Q" were not used)
Z = 1963
AA = 1964
Here is a link
https://gun-data.com/harringtonrichardson2_modern.html
Prior to 1940, there were no alpha characters used with the serial numbers as best that I can determine.
Any interest in factory wood grips?
lmd