CETME CETME is an acronym for " Centro de Estudios Técnicos de Materiales Especiales " ( Center for Technical Studies of Special Materials ) , a Spanish government design and development establishment . While being involved in many projects CETME was mostly known for its small arms research and development . The CETME rifle is its most famous project and the CETME name is most often used to refer to this rifle . CETME also designed the CETME C2 a 9mm advanced Sterling - like submachine gun , and the CETME Ameli ( AMEtralladora LIgera ) a light machine gun in 5 . 56×45mm NATO . CETME Rifle . The CETME rifle was designed primarily by the German engineer Ludwig Vorgrimler , who based his design on the experimental German StG 45 ( M ) and the French - made AME 49 . The StG45 used a roller - delayed blowback mechanism somewhat similar to the roller - locking system patented by Edward Stecke in the 1930s in Poland and used in the MG42 . The MG42 locking system actually locks completely and requires a short stroke barrel that travels backwards to unlock , compared to the StG45 ( M ) system that never completely locks and does not require a moving barrel . The CETME design inherits the StG45 ( M ) ' s fixed - barrel . The first prototype rifles fired the same 7 . 92x33mm Kurz round as the StG45 , and a variety of experimental 7 . 92 and 7 . 62mm cartridges were tested before settling on the 7 . 62×51mm CETME . This round was dimensionally identical to 7 . 62×51mm NATO , but with a lighter bullet and powder charge to reduce recoil , making fully automatic fire more controllable . Due to feedback from Heckler & Koch , the production rifle was chambered for the more powerful 7 . 62mm NATO . The Model B went on to be the foundation of the widely - deployed Heckler & Koch G3 battle rifle . The CETME Model A began manufacture in Spain in 1957 . The CETME series of battle rifles was manufactured in five models , the A , B , C , L , LC and LV models . The primary difference in the three first models is the absence of bipod and the lightweight C model , and the fact that the L , LC and LV models fire the smaller 5 . 56×45mm NATO cartridge . Models . Modelo A and A1 . Developmental prototypes . Modelo B . Production model , with a perforated steel handguard and chambered for the 7 . 62 x 51 mm CETME round . The 7 . 62 mm CETME differed from the standard 7 . 62 mm NATO round by having a lighter - weight bullet and a smaller propellant charge . The parts for these for the most part interchange with the later " C " model rifles . The Spanish Army adopted a variant of the Model B rechambered for the more powerful 7 . 62x51mm NATO round as the Modelo 58 Assault Rifle in 1958 . The Modelo B could be converted to fire the 7 . 62mm NATO round if the bolt group and return spring are replaced with that of the Modelo 58 . Modelo C . The " C " model was a lightweight version that was chambered for the 7 . 62x51m NATO round . It was adopted by the Spanish Army , Air Force , and Navy in 1964 . Modelo E . The CETME Modelo E replaced the wooden parts of the stock with plastic and the steel components with aluminium . After a short period on the production line , it was discovered that they were weaker than the previous models and that continuous fire deformed the firearms rapidly , and due to this , relatively few were produced and they were quickly discontinued . CETME L and LC . The CETME Model L was a downsized variant of the CETME system , chambered for the 5 . 56×45mm NATO cartridge . It was adopted by the Spanish Army in 1984 and was in service until it was replaced by the Heckler and Koch G36 rifle in 1999 . Civilian Versions . In the late 90 ' s Century Arms International ( CAI ) began offering semiautomatic only civilian versions known as the CETME Sporter , which are manufactured from assembled military surplus and US made parts . Although largely built from Model " C " parts , there have been reports of model " B " parts in the Model " C " Century built rifles . Due to the restrictions against importing receivers of select fire weapons , all receivers for these civilian versions are made in the US . Earlier receivers were of cast stainless steel , while later receivers were made from stamped and welded steel . Earlier rifles retained the wood furniture of the originals while later examples were available with Heckler & Koch style composite stocks . Due to state and local laws restricting weapons with assault weapon features , the CETME Sporter is also available with a permanently pinned muzzle brake rather than the original flash hider . Both civilian . 308 Winchester and NATO 7 . 62x51mm ammunition may safely be used in the CETME sporter . Reviews of the reliability and accuracy of these civilian versions have been mixed , with earlier versions generally being considered more reliable and accurate than later examples . Other CETME weapon designs . CETME C2 . The CETME C2 is a Sterling type SMG . CETME Ameli . This model was an unsuccessful attempt to replace the MG3 with a 5 . 56 mm Light Squad Automatic Weapon . The prototypes of the weapon were quite good , having good if not excellent performance in trials and first units , being tested not only in the Spanish army but by the British 22nd SAS regiment in 1984 , beating the FN Minimi and HK33E . Production examples had far less quality , with poorer materials . The British Army returned their serial production units ( a total of 600 purchased for SAS , SBS , and paratroopers ) to Santa Bárbara and Spanish Army units never fully replaced MG3 ( which is still in service ) with AMELI ( with only about 300 units in service and many units with functional problems due to low quality materials ; further orders were cancelled ) . Both models are reportedly going to be replaced with H & K MG4 . Spanish marines lightly modified the weapon adding reinforcements and additional weldings in order to correct some functional problems .