only just seen this post!

This was a reply I had from HW when I enquired about the date of my HW77 just before I sold it last year

Hello James,
thank you very much for your e-mail.
The air rifle HW 77, cal. 5,5 mm with the number 1011026was delivered in 1984.
Best regards Hans-H.
Weihrauch

23 yr old it was and the most accurate springer Ive ever shot