High-Stress Load Parts
Frames, receivers, slides, bolts and breechblocks, and cylinders bear high stress loads. Due to firing pressure, movement, or a combination of both, the parts must be strong and fabricated for safety and reliability. The fabrication of these parts is remarkably similar.
In some designs, the barrel extension (projection that extends rearward from the breech end of a barrel) can be considered a stressed part. Barrel extensions are most common in semiautomatic handguns (e.g., 9 mm M1908 Luger and the 22LR Ruger Standard Auto). They can also be observed on the breech end of barrels of Remington Model 870 shotguns.