Nice of the Belgians to tell us exactly the bore and muzzle constriction, weight of the barrels at time of proof, and load (only 1897-1903) for which the gun was designed.
12g
Manufacture Liegeoise likely proved with Mullerite for a service load of 2.70 grams = 41.67 grains = 3 Dr. Eq. (42 grains) "E.C." No. 1 or "Schultze" with 36 grams = 1 1/4 oz. shot.
Note bore 22 cm from breech was 18.2 mm = .716". After WWI bores were generally 18.4 = .724"; honed to .729" would only be a loss of .0025" of barrel wall
IF perfectly concentric.
If originally .716" and honed to .730" would be loss of .007" barrel wall.
Hybrid Mode