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 J. E. Browning (half brother of John Moses Browning) and was a recoil-operated design weighing 9lb 9oz and using 108 parts.
The Colt 1929 rifle was deemed unfit for further testing by the government because of poor feeding, poor cooling ability, an overly long receiver and short barrel, too many parts, and being too heavy overall.
FYI the hi-res pictures 1, 2, and 3 are cut off half way down. The thumbnails are unaffected. Chrome shows a black background for the bottom half of these pictures, Firefox shows completely through (e.g. no background).