? on Belgian Allin conversion of US muskets

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?

The U.S. Springfield Trapdoor Rifle Information Center
i would put the question to these guys.--charles

Thanks for the lead. I posted a request there---will see what happens. Best, p.