US Thompson .276 semiauto

This rifle was submitted to the 1929 US Army rifle trials. It was a .276 caliber retarded-blowback action, and used lubricated cartridges. It used paperboard clips for loading, much like contemporary Swiss rifles. Two versions of the rifle were submitted, the second being shorter and a pound lighter than the first.

The second model was put into testing, but broke its bolt after firing 1,106 rounds. It was withdrawn from testing, and deemed by the testers to have poor operating and feeding mechanisms.