CETME rifle

The CETME Model 58, is a stamped-steel, select-fire battle rifle produced by the Spanish armaments manufacturer Centro de Estudios Tecnicos de Materiales Especiales (CETME). The Model 58 used a 20-round box magazine and was chambered for the 7.62×51mm NATO round (although originally designed for the reduced power Spanish 7.62×51mm cartridge). The CETME 58 would become the foundation of the widely deployed German Heckler & Koch G3 battle rifle. Semi-automatic variants were also produced for the civilian market.

Development
The CETME (Centro de Estudios Tecnicos de Materiales Especiales) 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 MG 42. 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. However, the CETME Model 58 introduced a novel solution to the problem of cartridges sticking in the chamber. That is a fluted chamber, which are horizontal grooves in the chamber, that allow the cartridge cases to float on a layer of gas to aid extraction. The horizontal marking left on spent cartridge cases has become a signature of this design.

The first prototype rifles fired the same 7.92×33mm 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.

Production of the rifle began in Spain in 1957. The CETME series of battle rifles were manufactured in four basic models; the A, B, C and E models. The primary difference in the production models is the modes of fire, the absence of bipod and lighter weight for later models.

Model A
The Model A's were the developmental prototypes. These models were unusual as they fired from the closed bolt in semi-automatic and from the open bolt in full-auto mode. Later production models fire from only the closed bolt. The Model A's are easily identified by the position of rear sight and bi-pod folded back to form fore-stock.

Model B
The Model B was the first production model. It had a perforated steel handguard and chambered for the 7.62×51mm CETME round. The 7.62 mm CETME differed from the standard 7.62mm NATO round by having a lighter-weight bullet and a smaller propellant charge. The parts for the Model B are for most part interchangeable with the later Model C rifles.

The Spanish Army adopted a variant of the Model B re-chambered for the more powerful 7.62×51mm NATO round. The Model B could be converted to fire the 7.62mm NATO round if the bolt group and return spring are replaced with that of the Model C.

Model C
The Model C was a lightweight version that was chambered for the 7.62×51mm NATO round and had wooden fore-stocks. The Model C is virtually identical to the Model B. However, certain components had been strengthened to better deal with the increase power of the standard 7.62mm NATO round.

It was adopted by the Spanish Army, Air Force, and Navy in 1974.

Model 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 1990s 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 aluminum, 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 7.62×51mm ammunition may safely be used in the CETME sporter.