American Rifleman by Dave Campbell - Thursday, December 13, 2018
G3A3
A war is similar to a forest fire. When it has run its course, it leaves behind a tattered skeleton of broken infrastructure and torn-apart people. And while the destruction may be ugly and devastating, often what grows from the ashes can be remarkably fresh and new. In the forest, new plant growth that will feed newer crops of wildlife. Closer to civilization, new businesses spring up, spawning growth, new homes and seemingly boundless opportunities for success.
So after Germany's defeat in World War II its people began another round of improvements that they hoped would allow them to compete on the world stage. German manufacturing has enjoyed a long reputation for producing quality products made to exacting precision. As far back as America's Colonial times it was the German gunsmiths who developed the effective and elegant Pennsylvania flintlock rifles based upon the jaeger gewehrs from their vaterland. Relentless bombing of the Waffenfabrik Mauser AG factory at Oberndorf, along with the systematic dissolution of the factory and its records by French occupation forces, had destroyed the famous firearms and ammunition manufacturer.
Three former Mauser engineers, Edmund Heckler, Theodor Koch and Alex Seidel, salvaged what they could and in 1948 opened a machine tool plant on the old Mauser site. A year later the company registered its name—Heckler & Koch GmbH (H&K)—and began producing bicycles, sewing machine parts and other precision tools. When West Germany put out a bid request for a new rifle for its German Federal Army, H&K responded with its version of the Spanish CETME rifle.
Though built in and primarily for Spain, the CETME was actually a German design led by Ludwig Vorgrimler, an engineer with some history at Krupp and Mauser. This rifle’s design roots are in the StG45(M) and the French AME 49 sturmgewehrs, which were chambered for the 7.92 x 33 mm Kurz and .30 Carbine cartridges, respectively. However, the CETME Model A was configured as a battle rifle, chambered for the 7.62 x 51 mm CETME cartridge, a round slightly less powerful than the 7.62 x 51 mm NATO round. Its lockup system is wrapped around a roller-delayed blowback system whereby the bolt has a pair of rollers crammed into corresponding recesses in the barrel just behind the chamber. The rollers are held in placed by spring tension applied to a tapered locking piece within the bolt. As the chamber pressure works against the bolt, the tapered locking piece retards the bolt velocity by delaying its engagement with the rollers. When the locking piece has moved rearward enough, the rollers are compressed into the bolt body, freeing the bolt to move rearward and cycling the action.
This delayed-roller blowback operation was first seen in the Mauser Gerät 06H, a prototype sturmgewehr developed in the latter months of the war. Though some early prototypes featured a gas piston, the CETME and other rifles and submachine guns built around the principal do not use a piston or operating rod. Delayed-roller-blowback guns are lighter than corresponding gas-operated arms, but initially they had a problem with cases sticking in the chambers, thus tearing off extractors. The CETME addressed this issue by machining horizontal flutes in the chamber. These flutes allow some combustion gases to flow rearward and jolt the case enough to free it for otherwise normal extraction and ejection. By the way, although the fired cases look terrible, they can be cleaned and reloaded.
More:
https://www.americanrifleman.org/articles/2018/12/13/a-look-back-at-the-heckler-koch-g3-rifle/
