French army began the search for a semi-automatic military rifle as early as about 1900. It was a secret "government-only" program with the goal of replacement of obsolescent Lebel M1886 rifle. After much development, conducted at four government arsenals, and extensive trials that included as much as 20 different designs, in 1910 French army selected a Meunier Rifle, chambered for the new 7x59 rimless ammunition. Only about 1000 of Meunier rifles were produced before the start of the Word War One, and further production was ceased to avoid complication of supply, because main body of French army was still equipped with weapons firing old 8mm Lebel ammunition. Still, French army wanted a self-loading rifle, and in 1917 it adopted a new weapon, designed by Ribeyrolle, Sutter and Chauchat (hence the RSC acronym), authors of the infamous CSRG M1915 "Chauchat" light machine gun. The new rifle used "old" ammunition and made a good use of available parts, produced for obsolete Lebel rifles, including stock parts, barrel and tubular magazine. This rifle, officially known as Le fusil automatique de 8 mm RSC modele 1917 or RSC Mle.1917 in short, was produced and issued to French troops in significant numbers. Some 80 thousands of RSC M1917 rifles were produced at MAS (Manufacture d'Armes de St.Etienne) armory during 1918, using some parts supplied from MAT and MAC factories. After the Armistice, the basic pattern of rifle was slightly changed - barrel was shortened, some parts modified, and magazine was altered to accept standard 5-round clips produced for Berthier bolt-action rifles. This became the RSC M1918, which was also produced in some numbers (about 10 thousands) shortly after the war, although the main body of French army was still equipped with bolt-action rifles when World War Two broke. It is also interesting to note that during late 1930s many of RSC M1917 and M1918 rifles were converted by French army to manually operated, bolt action rifles by blocking the gas port.
It must be noted that before and during WW1 French army was in many ways well ahead of its time in tactical and technical concepts. In fact, France was the only major world power that attempted to arm its infantry with mass-issued semi-automatic rifle (as opposed to "specialist" weapons issued by Russian army in the form of Fedorov's Avtomat, or very limited use of Mondragon semi-automatic rifles by Germans).
RSC Model 1917 rifle is gas-operated, magazine fed weapon that fires in semi-automatic mode only. It uses conventional gas piston system with long stroke piston, located in the gas cylinedr below the barrel (formed by the former magazine tube of Lebel rifle). return spring is located behind the gas piston, in the rear part of same ex-magazine tube. Gas piston is connected to the bolt group by the bent operating rod, which runs toward the cocking handle on the bolt at the right side of receiver and stock, below the removable steel cover. Locking is achieved by rotating the bolt head, which has two sets of radial lugs that engage respecive cuts made on the inner wall of tubular receiver. Feed is from integral box magazine, using proprietary en-block clips which hold 5 rounds of ammunition in single row. Clips are loaded into magazine through the bottom of the gun, by unlatching the magazine cover and opening it down and forward. On M1918 rifles magazine was changed to accept standard issue Bertheir M1916 en-block clips, and las shot bolt hold-open device was added. Manual safety was located on the left side of the gun, above and in front of trigger guard. Either version of rifle was capable of mounting standard French M1896/15 bayonet.