The M-1878 was the first of the "modern" Nagant revolver designs...The M-1878 (also known as the Officer’s Model, as they were issued almost exclusively to Belgian Army officers)...The M-1878 was withdrawn from official Belgian service just before World War 1, but still saw some use in that war. The M-1878 was replaced in 1886 by the M-1878/86 version (also called the M-1886); this version is essentially the same as the M-1878 for game purposes, though the grip shape allows the M-1878/86 to sit better in the hand. The M-1878/86 was used by the Belgians until 1940, though after World War 1, the primary user was the Belgian Customs Service.