I have inserted foot in mouth on more than 1 occassion trying to date a Belgian gun. I used to go by the date stamp (often missing) or the controller's mark (not very accurate). It has been and continues to be a learning experience.
For what it is worth... Some marks with dates:
Crown over ELG with star at bottom, acceptance of proof at Liège, 1893-1968.
The lion over the PV which indicates nitro proof in use 1898-1968.
Barrel weight, 1.169 Kg . This started in 1892, after 1924 fractional weights (eg 1.169.1) were no longer used.
Lion over PV, nitro proof, 1898-1968.
Crown over ELG with star at bottom, acceptance of proof at Liège, 1893-1968.
CHOKE, 1897-1898
CHOKE 17.0, 16.3, 1898-1924
CHOKE 18.0, 1924-1968
70/20.6, 1892-1924
inside a diamond 16 over C, 1898-1924
inside a circle 12-70, 1924-present
The Kennett articles in GunDigest. You can usually find a copy on eBay for $5 or less.
22nd Edition Czecheslovakia -1968
23rd Edition Austria Hungary & Austria - 1969
24th Edition France - 1970
25th Edition Spain -1971
26th Edition Italy - 1972
27th Edition Hungary - 1973
28th Edition Russia - 1974
29th Edition Germany -1975
30th Edition Military - 1976
31st Edition England - 1977
32nd Edition Belgium - 1978
33rd Edition India -1979
If any of the above is not accurate, please correct it.
Thanks,
Pete