By the late 1850’s Portugal had ceased to be a global power and by the early to mid-1860’s its influence consisted of mostly areas in Africa. It was during this period that most European Nations were modernising their armies, while Portugal had most of their investments in their naval capabilities or protecting their colonies with very little on internal security and military technology. Portugal was still at that stage using the Westley Richards percussion rifles and pistols, while the Navy were using the Beaumont-Adams percussion revolver since 1863, while some members of the Lisbon and Porto Municipal Guards were using the Galand-Sommerville .450 Cal. revolvers. Although the search was underway to replace and modernise the Portuguese rifles that led to the adoption of the Guedes/Kropatschek design, little was done in the beginning in the way of research into a suitable side-arm for the Army. After trials of various revolvers, from the 1873 commission, it was decided in late 1877 to adopt a modified version of the Chamelot-Delevigne system, originally developed by firm of J. Dechourin, Fils, of St. Etiénne, France using the system invented by the engineer George Abadie and who sold the manufacturing rights to the firm of L. Soleil et Fils, from Liège in Belgium, There is however some speculation as to whether it was George Abadie, or Isaac Ishmael Abadie who did the actual development, as there is no clear record of which one it was, and both were employed in the Liège gun trade at the time.
The distinguishing feature of the M1878 revolver was the loading system patented by Abadie and sold to the firm of Soleil that allowed it to be loaded as quickly as a top-break revolver. There is a very good YOUTUBE VIDEO from the folks at C&Rsenal to describe the working of the Abadie system. By opening the loading gate, the trigger no longer operated the hammer, allowing the gun to loaded by pulling the trigger to rotate the cylinder. During 1886 Ministry of War decided to issue the revolver to Artillery and Cavalry as well as replacing the old Galands still in use by the Lisbon and Porto Municipal Guards. The M1886 had the barrel lengthened to 142mm, otherwise there was very little difference from the older M1878 and was acquired from the firm of Simons, Jarrisen & Dumoulin who had taken over the Soleil firm. (Erlmeier, Brandt Ref. 141).
Sources: Regalado, J. Revolver Abadie m/1886 da Guarda Municipal. Revista de Guardia, GNR, Issue nº 1 – January/March 2008
Pinto, RFM. The Military Industries and Portable Firearms in the Portuguese Army. The Military Magazine nº 1, of 1878
Both adapted from Armamento Militar do Exército Português (Web)