Interesting and thanks for posting Ryan.
It may be a Manufacture Liegeoise. Just forward of the flats on both barrels there is a Crown over something - could it be 'ML'? 'LD'? (Lambert Dumoulin)
The lettre annale is probably a 'f' = 1927
It carries Smokeless Proof which was mandatory after 1924.
The chambers are 65mm = 2 1/2"
The 'choke' mark only means a muzzle constriction > 2 mm or .008".
Is there nothing on the rib?
Unfortunately there is very little interest today for well used but not abused 12g Belgian doubles with 2 1/2" chambers, and the crossover stock diminishes the number of prospective buyers much more.
