On October 1, 1928, the US War Department published a request for semiautomatic rifle designs. The Colt company submitted this .276 caliber rifle to the ensuing trials in 1929. It was designed by Jonathan Edward "Ed" Browning (half brother of John Moses Browning) and was a recoil-operated, tilting bolt design weighing 9lb 9oz and using 108 parts. The tilting bolt system was derived from the 1911 pistol system as designed by John Moses Browning, and the operating system also used an accelerator reminiscent of JMB's Model 1917 and 1919 machine guns.
After the trials, the Colt 1929 rifle was deemed unfit for further testing by the Ordnance Department because of poor feeding, poor cooling ability, an overly long receiver and short barrel, too many parts, and being too heavy overall. Ed Browning would take the design back to his workshop and continue working on it, eventually replacing the short recoil operating system with an annular gas piston, and bringing it to the Winchester company in the late 1930s.