The US military spent many years searching for a semiautomatic rifle design suitable for general issue. They eventually chose the Garand gas-operated rifle, but there were many other interesting rifles involved along the way. The early designs we have information on are:
Colt 1929 rifle
Danish Bang rifle
Swiss Rheinmetall 1928 rifle
Swiss Rychiger rifle
Pedersen .276 rifle
Thompson .276 rifle
White .276 rifle
Winchester .30 rifle