Acier Cockerill (ACL) made the steel, under license from Siemens-Martin
LLH made the "rough forged tubes"
LePage (likely) joined, fit and finished the barrels
http://www.littlegun.be/arme%20belge/artisans%20identifies%20l/a%20lepage%20manuf%20armes%20gb.htm
or maybe it was 'HB' who did the barrel work?

Could you please post a full size close up of the 'HB'? - that is not in PeteM's list
http://damascus-barrels.com/Belgian_Trade_Marks.html