The .276 caliber Pedersen was the primary competitor to the Garand as the first US military self-loading rifle. It used a Luger-style toggle action. Its main flaw was that it required lubricated cartridges. This lubrication came in the form of a thin and hard wax coating which was not obvious to the casual shooter, but it was made a significant argument against the Pedersen and for the Garand rifle. The Pedersen also was heavier and used more parts than the Garand design.
US Patent 1,062,604 (John D. Pedersen, Gun-Operating Cartridge, May 27, 1913)
US Patent 1,123,362 (John D. Pedersen, Cartridge, January 5, 1915)
Vintage news clippings, plus Aberdeen Proving Ground photos (click here to download the whole gallery in high resolution)
Original 10-round clip of .276 Pedersen