Bob is an invaluable, and much appreciated resource, and his record for SN 28032 is no doubt correct.
Your SN 28032 however clearly carries a 1926 lettre annale, the date code placed by the Liege Proof House at the time of proof, and lettre annale are correct.
Belgian guns can not be dated based on the controller's marks - some were repeated and the significance of some were lost to a fire.
In addition, the 12-70 in the Omega was only used after 1924

[Linked Image from photos.smugmug.com]

https://sites.google.com/a/damascusknowledge.com/www/home