the term Belgian rifle is perhaps the most generalised of all CW guns, as the Liège arm trade sold all kinds of arms - and not only those that were actually and new produced. New produced Belgian guns were mostly those mentioned by John (= French pattern two or three band with back action locks) but also the well known "Brazilian Light Minié" rifle by Drissen & Co, Liège (an Enfield/French mixture) or the Piedmontese rifle musket (Falisse & Trapmann, Francotte, both Liège). They also produced Enfields for the British government but due to their exclusive contracts with them I dont believe any of the Belgian Enfields were sold to America. Some of the numerous German states ordered their guns in Liège (with Liège stamps = Belgian arm for the contemporaries):
Sachsen .58 Dresden rifle (Saechsisches Schuetzengewehr): Malherbe, Liège
Sachsen-Weimar (rifled musket and rifle): Malherbe, Liège
Luebeck (rifled musket): Lemille, Liège, as well as Bremen.
Many other surplus of European obsolete guns, including Prussian 1809 U/M, were negotiated by Belgian gun traders and came to America in chests with a Belgian address (= Belgian guns?). There is only one documented sale directly to the CSA (mentioned in another thread here) however other sale may have occured as well as captured Union import guns may have found their way in the South and could have been used by CS troops.

Regards,

Marc