Bonjour Maxime,
Comment allez-vous si chanceux?
First, it is not an M1843/44, it is a M1862. The M1862 was lower than the earlier versions, and it had brass visor trim and screw posts. Earlier versions had no visor trim like a Tschako and extended posts. Normally there is leather or cord trim around the top, but this seems correct. Liner is correct for all issued Tschapka. Do have a close-up of the eagle Wappen? These are very unique, especially with the tail feathers, but this one appears to be a correct pre-1860 eagle Wappen. I used to have one and like an idiot, I traded it away. Feldzeichen is missing of course.
It would be for Ulanen-Regt. Kaiser Alexander II von Rußland (1.Brandenburgisches) Nr.3 or Lithauisches Ulanen-Regt. Nr.12.
Veuillez me dire si vous ne l'achetez pas? Bonne chance, Tony