Could it be Swedish?

Choke in Swedish is surprisingly choke.

Stil in Swedish means style (and that is why I always thought the stamp is not referring to a type of steel - it refers to the style of the shotgun and that is why it is repeated four times - also on the action not just on the barrel flats.

Full in Swedish is fullständig but it is often abbreviated to simply ful

Well....surprise! surprise!

Still looking into the crown stamp with the letters...any help with that would be great.