Then you have the same version as mine. And if you look carefully, I think you will find that it is marked not 1866, '77 and '80 but 1866-74 and 80.

1866 The year of introduction of the Chassepot rifle
1874 The year of introduction of the Gras rifle. I.e. you have a Chassepot needle rife converted to take the Gras cartridge.
1880 The "upgrade" with a gas escape groove milled in the left side of the receiver.

The bayonet is the right type for your rifle. Rifle + bayonet make an awesomely long combination.


Patrick