same commentary on its wikipedia ☞ en.wikipedia.org/wiki/Chauchat

The Mle 1915 Chauchat’s performance on the battlefield drew decidedly mixed reviews from the users when the war was stagnating in the mud of the trenches in 1916. This brought about a survey, regiment by regiment, requested by General Pétain in late 1916; the survey’s essential conclusion was that the open-sided half-moon magazines were defective and caused about two thirds of all stoppages. For instance, it was a common practice for the gunners to oil up the inside of the magazines to facilitate movement of the 8mm Lebel rounds. Also, loose earth, grit, and other particles easily entered the gun through these open-sided magazines, an ever-present risk in the muddy environment of the trenches. An insistence on using only good, undeformed magazines with strong springs was the most practical solution to this problem. Chauchat gunners were also known to load their magazines with 18 or 19 rounds, instead of the maximum 20, in order to avoid the dreaded first-round failure to feed. The Chauchat’s long recoil system is often cited as a source of excessive stress on the gunner when firing, though recent and extensive firing tests have demonstrated that it is the Chauchat’s ergonomics and its loose bipod, rather than its recoil, that makes it a difficult gun to keep on target beyond very short bursts. On most of the Gladiator-made guns, the sights also made the Chauchat shoot systematically too low and to the right, a failing which was soon recognized but never corrected. Overheating during uninterrupted periods of full automatic fire (about 120 rounds with the 8mm Lebel version) often resulted in the barrel sleeve assembly locking in the rear position due to thermal expansion, causing stoppage of fire until the gun had cooled off. Hence, French and US Army manuals recommended firing in short bursts or semi-auto. In 1918, the A.E.F. officially labeled the Chauchat in its user manuals as an “automatic rifle”, a product of mistranslation of the term “Fusil Mitrailleur”, instead of “Machine Gun Rifle”, a more accurate description.