Thanks Bunker9939 for your input. All conversation is valued here; this is how we all learn.
I trust your database since I do not have one. Could you write more about it? I wrote circa 1967 to hedge my bets because I do not really know.
Since I have not done the research you have done, nor read the posts you have, what about the theory that in year 1, 1956, they started at serial number zero and went up to 1 million; then at the beginning of 1957, they added 1 million and another million each year.
It would be nice if the Chinese would open their books like Izhmash and Tula have (not). In any case, I think we are in the ballpark with the dating system whatever you subscribed to. If it is 1966 that is fine with me. That makes my 11 million Type 56 even earlier, 1965. Is there a thread here discussing this serial number dating system? I have not found one. If not, maybe you should start one. I would enjoy reading it as would others new to the Vietnam era Chinese Type 56.
As for this particular rifle, if it is an L and D marked 11M, then it is an anomaly. Perhaps a test run given it is apparently the 1943rd one made in that year. I will see if I can get a message to Brayley to settle this question.
Could you post photos of information about the 12M with L and D markings? That would be great.
We are looking forward to reading more.