| 摘要 |
An improved firearm includes in some embodiments a gas block of an indirect impingement system mounted on the barrel near the firing chamber to provide gas at a higher pressure for moving the piston that moves the bolt carrier. Some embodiments include low frictions rails on which the bolt carrier moves within the upper receiver. The higher gas pressure and the reduced friction from the rails reduce the required stroke of the piston, allowing a shorter firearm to be constructed. In some embodiments, mating elements, such as pins and corresponding openings, on the upper receiver and the lower receiver, align and provide additional structural strength to the upper and lower receiver. |
