The Model 1922 Bang rifle using the sliding muzzle-cap system.
The Model 1922 Bang rifle is a US semi-automatic rifle designed by the Danish arms designer S°ren Hansen Bang. It was a modification of the earlier Models of 1909 and Model 1911 Bang rifles, both chambered in the .30-06 Springfield round.
It was gas operated, using a sliding muzzle cup system which was blown forward by the combustion gases while the bullet emerged from the barrel. During field trials in 1919 and 1927, the rifle was demonstrated by the designer. Because of its mechanical complexity and its susceptibility to gas fouling of the sliding muzzle cup, it was unsuccessful in US government testing.
The Bang System was also used in the Gewehr 41 and suffered the same shortcomings. The controversial French St. ╔tienne Mle 1907 machine-gun and its precursor, the unsuccessful Puteaux APX machine gun of 1904, were also actuated by a blow-forward gas system inspired from the Bang semi-automatic rifle.
Technical short: Blokesplaining the difference between a G41 and a "Bang" gas system