The Belgian Army was the second to adopt the Chauchat automatic rifle, after the French. Almost all of Belgium was under German occupation during World War One, leaving Belgium significantly dependent on French aid for arms during the war. The initial Belgium purchases were standard 8mm Lebel CSRGs, but by 1917 Belgian engineers were working on a solution to convert the guns to the Belgian standard 7.65mm Mauser cartridge. This was completed by the end of the war, and the Chauchat remained a standard arm of the Belgian military after the war.
Work to improve the design continued, and an upgrades version was formally adopted in 1927. This included the 7.65mm conversion, with the best magazines made for any model of the Chauchat, as well as a series of dust covers to close off every hole in the gun (magazine well, ejection port, charging handle slot, and barrel shroud vents). The Belgians also replaced the original bipod with a much better type (similar to what they would use on the FN BAR), simplified the feed system, and added a tension latch to ensure reliable operation.
This new pattern of CSRG would be standard Belgian front-line armament until the FN BAR was adopted in 1930. The Chauchats were still in service with some until at the beginning of World War Two though, and saw service at that time.
Thanks to the Liege Arms Museum for access to film this for you! If you are in Belgium, definitely plan to stop into the museum, part of the Grand Curtius. They have a very good selection of interesting and unusual arms on display.