47 mm Model 1931 anti - tank gun The Royal Cannon Foundry 47mm anti - tank gun Model 1931 ( , abbreviated to " C . 47 F . R . C . Mod . 31 " ) was an artillery piece developed in 1931 for the Belgian army which saw widespread service in the Battle of Belgium in 1940 . It was colloquially known as the " ' Quat ' sept " ( Forty - seven ) by the soldiers that used it . It was developed by the firm F . R . C . , the Herstal - based " Fonderie Royale des Canons " , not to be confused with the French F . R . C . Versions . Both infantry and cavalry versions of the gun were produced with minor variations : the cavalry version had pneumatic tires for greater road mobility , while the infantry versions had heavier but more durable full - rubber tires . The gun was also able to be incorporated into fixed defenses and bunkers , including the Belgian fortifications at the Albert Canal . They were also fixed to the T - 13 tank destroyer . Performance . Regarding its time of development , the ' 47 ' had an impressive performance , especially in comparison to contemporary German or French designs - respectively the 3 . 7 cm Pak 36 and 25 mm Hotchkiss anti - tank gun . In medium range armor penetration it even outperformed the British Ordnance QF 2 - pounder : armor piercing rounds could penetrate 47 mm of armored steel at a range of 300m . This was largely due to the heavy caliber with a shell weight of 1 . 52 kg for the armor piercing rounds . However , this performance came at a price : with a total weight of 515 kg , not including ammo or equipment , the ' 47 ' was a lot heavier then the German Pak 36 ( combat weight 327 kg ) . Being a compact design , the ' 47 ' was easy to conceal , but as a consequence of its heavy weight and the general lack of mechanization in the Belgian army of 1940 , repositioning the gun was a difficult task . Service History . Second World War . Belgium . Over 750 47 mm guns were in service in the Belgian army at the time of the German invasion in 1940 . All active and first reserve infantry units , cavalry units and units of the border guards were equipped with the gun , while the second reserve units had to make do with older anti - tank rifles . Every infantry regiment consisted of 3 battalion s of rifle infantry and a single heavy arms battalion . This in turn consisted of 3 heavy weapon companies , one of which was equipped with 12 47mm anti - tank guns Model 1931 . . Given its good armor penetrating capabilities , the ' 47 ' could penetrate the 30 mm armor of the German Panzer III and Panzer IV tanks from a range of over 500m . Reports of panzers knocked out by the ' 47 ' during the Battle of Belgium do exist , but in general the bulk of the Belgian army was deployed in the north of the country , on the flat terrain of Flanders , and not in the hilly terrain of the Ardennes in the south , which was regarded as impenetrable but nonetheless served as the primary route of invasion for about 2 , 500 German panzers . Hungary . Several hundred 47 mm guns were captured by the Germans after the battle of Belgium and donated to the Hungarians in 1940 - 1 , to make up for their lack in anti - tank guns during Operation Barbarossa . Their use was limited however due to a lack of spare parts , while the armor penetrating capabilities of these guns had also been surpassed by the Soviet advances in tank construction . Most were relegated to training duties .