I have the list. It is good for all H&R's, from 1940, until the H&R bankruptcy in 1986.
It is NOT for sale, at any price!
That being said, I will tell you what year your pistol was made, if you give me the letter prefix, and $ 10.
Here is a link to the list
Actually this only goes through 1982. Here are the prefixes through 1986.
After the bankruptcy, it gets a bit weird, and I really have no interest in those H&R/NEF 1871 pieces, so I don't even pay attention to the later models.
I have seen a list of all the later pieces, but I don't remember where.