The CETME Model 58 holds its origins in the StG 45(M) assault rifle prototype of World War 2. This automatic weapon was in the stages of design during the last few months of the war and only completed in extremely limited numbers - perhaps as few as 30 examples were in circulation - before the end of the war in Europe in May of 1945. Design of the weapon was attributed to Wilhelm Stahle and work on the type began in 1944 under the charge of the fabled Mauser concern. The system was chambered the fire the 7.92x33mm Kurtz (Short) intermediate cartridge and, what made it most unique, it attempted the firing action from a "roller-delayed blowback" assembly first tested in an experimental MG 42 machine gun. This operation essentially involved two locking rollers situated to either side of the firing pin near the base of the cartridge, engaging the sides of the receiver during the firing action and delaying the movement of the bolt head - the barrel remaining fixed in place. The principle was adopted as a cost-effective alternative to the proposed gas-operated, roller-locked breech system intended for the StG 45.
Following the war, many German engineers left Germany proper and some of the Mauser engineers landed in Spain working for the government-run Centro de Estudios Tecnicos de Materiales Especiales ("Technical Studio of Special Materials") - or better known in its abbreviated form as "CETME". Further development of this delayed blowback system ensued until it was refined to the point of proving viable in a rifle frame. Like the original Mauser design, the new automatic weapon was also chambered for the 7.92mm cartridge.
Intent on selling the design to an interested party, the technology was showcased to the West German Army through the Dutch. However, Germany was intent on finding a logistically friendly service rifle in line with the 7.62x51mm NATO standard cartridge. The CETME group continued worked on their design attempt and produced an automatic rifle chambered for a reduced-charge 7.62mm cartridge (7.62x51mm CETME) for sale to the Spanish Army. The resulting product was then offered - and formally adopted - by the Spanish Army in 1958 under the designation of "Assault Rifle Modelo 58". This became the first recorded use of a service rifle utilizing the delayed blowback principle. The West German Army evaluated various competing designs and eventually centered on the CETME rifle - though slightly revised to take on the full-power 7.62x51mm NATO cartridge. License production was undertaken in West Germany as the Heckler & Koch G3 and entered service in 1959, going on to see widespread use around the world in countless conflicts. The Model 58, however, would not repeat this global success.
Outwardly, the CETME design certainly followed the lines of the German HK G3 but was an all-Spanish weapon through and through. It sported a solid stock attached to a well-contoured receiver containing all of the pertinent internal working components. The pistol grip was well-angled to the rear of the receiver for a firm, ergonomic hold while the curved trigger unit was set within an oblong trigger ring. The magazine well was ahead of the trigger group and accepted a curved, detachable box magazine with 20 rounds of ammunition. The barrel extended from the forward portion of the receiver and was capped by a flash suppressor. Internally, the CETME matched the HK G3 including its unique delayed blowback operation. A folding bipod was served as standard in original production models and joined at the barrel, aft of the muzzle. When folded, the bipod doubled as a forward grip area so the operator would not touch a hot barrel. Protection n this sense was eventually improved in later production models to help lessen the risk of exposure to the generated heat. The rifle was sighted through a front and rear installation.
Overall length of the CETME Model 58 was approximately 40 inches with the system relying on a 17.7 inch barrel. Weight was in the vicinity of 9lbs. The listed rate-of-fire was 550 to 650 rounds per minute with a muzzle velocity nearing 2,580 feet per second.
On notable change to the CETME Model 58 line occurred in 1974 when the Spanish Army officially made a move to the full-power 7.62x51mm NATO standard cartridge. This decision forced the CETME Model 58 to be internally reworked to accept the more powerful round. Marking this change, the revised rifle forms were designated CETME "Model C". The CETME Model C was then delivered in a 5.56x45mm form as the "Model L" which, in turn, served as the origination of the carbine "Model LC" - both variants appearing in 1988. Still another, even more compact form with many protrusions stripped, was issued to vehicle crews for firing from within their confined spaces.