FM 24 / 29 light machine gun The Fusil - mitrailleur Modèle 1924 M29 was the standard light machine gun of the French Army from 1925 until the 1950s and was in use until 2000 - 2006 with the National Gendarmerie . It fires the French 7 . 5mmx54 round which is equivalent in ballistics and striking power to the later 7 . 62×51mm NATO ( . 308 Winchester ) round . A robust and reliable weapon partly derived from the BAR action , the FM 1924 M29 soldiered on , practically without interruptions , for more than 50 years . Development . After the end of World War I , the French army sought to replace the problematic " Fusil - mitrailleur mle 1915 CSRG " light machine rifle ( better known as the Chauchat ) . French commanders considered standardizing on the American M1918 Browning Automatic Rifle ( BAR ) , but eventually required the development of a locally built weapon . MAS ( an abbreviation of Manufacture d ' Armes de St . Etienne - one of several government - owned arms factories in France ) proposed a direct derivative of the BAR , but the Manufacture d ' Armes de Châtellerault ( MAC ) won the bid with its weapon , which was partly derived from the BAR action . It had been formulated and designed by a Lt Col Reibel assisted by Controller Chosse . The FM Mle 1924 entered production in late July 1925 and saw first operational use in Morocco in May 1926 . It was immediately well received and even favorably compared in performance with the much heavier Hotchkiss machine gun . However problems created by the new 7 . 5mm ammunition did appear . In particular , 8mm Mauser ammunition which was used in captured Mauser rifles carried by auxiliaries in Morocco during the Rif War , could be chambered and fired with disastrous results . This situation led to the development of a slightly shorter 7 . 5x54mm round , which was retained in 1929 as the standard ammunition for all future rifles and light machine guns in French service . The modified " fusil - mitrailleur modèle 1924 modifié 1929 " ( FM Mle 1924 M29 ) was mass - manufactured ( 187 , 412 ) , beginning in 1930 . In addition to these newly manufactured guns some 45 , 530 older FM Mle 1924 ' s , already in service after phasing out the Chauchat , were rebarreled in order to accept the newer 7 . 5X54mm ammunition . Both the original " fusil - mitrailleur Mle 1924 " ( " automatic rifle , model of 1924 " ) as well as the modified Mle 1924 M29 have the same overall features : a folding bipod , an in - line stock , a pistol grip , a top - mounted 25 - round detachable magazine and a bolt hold - open after the magazine ' s last round had been fired . There are two separate triggers : the trigger in front for using semi - automatic fire only and the rear trigger for firing on full automatic . Protection of all the openings against mud and dust was excellent . The cyclic rate was 450 rounds per minute . In general , this new weapon was accurate and highly reliable but the barrel was screwed well into the receiver , as in the Browning Automatic Rifle ( BAR ) , and thus it could not be separated quickly and easily in the field as for the British Bren gun . The French Army instruction manual ( July 1925 ) recommends not to go beyond 400 rounds of uninterrupted firing since at that point the gun needs to be given a pause of ten to fifteen minutes in order to cool off . But instead , the French instruction manual recommends the following routine for the FM 1924 : fire 4 to 5 detachable magazines ( 100 to 125 rounds ) then take a short pause , then keep repeating that same restrained fire plus short pause routine which permits steady performance and very extensive firing periods . Operational use . The FM 24 / 29 was the standard squad - level automatic weapon of the French infantry and cavalry at the start of World War II . After the French surrender in World War II , the Germans captured large quantities of this weapon , which they used operationally until the end of the war . From 1943 on , as the French army was re - equipped and re - organized in North Africa with Allied support , the FM 24 / 29 was kept in service , as French troops considered it superior to the Browning Automatic Rifle . The FM 24 / 29 was the workhorse in the First Indochina War and served in the armed forces until after the end of the war in Algeria . It was replaced by the AA - 52 general - purpose machine gun in the 1960s , but it was still in use with National Gendarmerie regional brigades until 2000 - 2006 . Variants . Model 1924 / 1929D machine gun . The Model 1924 / 1929D machine gun was a variant of the MAC 24 / 29 , adapted to firing from interior firing ports in the bunkers of the Maginot Line . M1931 . A modified version of the gun , the M1931 , with a heavier barrel and drum feed was produced for installation in tanks and fortified emplacements . The rate of fire of this version was raised to 600 rounds per minute . Production ran from 1931 to 1940 .