Belgian manufacture of (US M1866) Allin trapdoor conversions?

Does anyone know of any other published accounts other than Edward Hall's "Belgian "Allin" Trapdoors" published in the August 1996 issue of Gun Report regarding Belgian manufacture of the UjS M1866 Allin conversion rifle?

Allin as inventor and superintendent of Springfield Armory patented the conversions signing over use to the US and retaining the right to manufacture the conversion elsewhere. His company was active in Belgium and a few were made up there using US locks and patched stocks. New receivers, sights and barrel were manufactured. Proofs are Belgian. The guns are unmarked and of unknown caliber. Can anyone add more information to the pot?

In those days everybody was trying to reuse the huge stocks of obsolete muzzleoaders. The closest I've seen is the Wanzl or krinka (sp). Most just copied the snider. If anyone would have altered us made muskets to the allen system in any quantity they should have been listed in the "arms of the world 1911 alfa" catalog or in Bannermans catalogs. Never seen one listed altho the alfa catalog offered us muskets in percussion and apparently "reverse enginneered" to flint. Both the alfa and the bannermans catalogs have been reproduced and are available. I like them as reference.