Ah well Mr Bellycrawler I can answer a few of those questions for you as I wrote the list in the first place --- though it seems to have been added to with some later serial numbers, which is great because it's what I hoped would happen.
1951 weihrauch started production.
The 100,000 numbers were published in Airgunworld in the early 1980s.
The one millionth gun was a gold plated HW35 and was featured on Airgunworld front cover in 1983.
Leather seal to synthetic seal serial number was published in the Airgun Book by John Walther.
The change point from 25 to 26mm on the 77 is from Chambers' and VMac's websites.
Introduction dates for the different MKs of 77 are from adverts in Magazines and Jim's announcement in SAR.
Most of the rest of the serial numbers and dates are taken from German, American and Italian websites with the dating coming from Emails from Weihrauch.
I just stuck everything together one night when there was nothing on telly and stuck it up on the BBS in the collector's section ---it's everywhere now.
All the best Mick