By 1932, the competition for the new US emiautomatic service rifle had been narrowed down to just two designs: John Pedersen's delayed blowback toggle action and John Garand's gas-operated action. Both rifles were chambered for Pedersen's .276 caliber cartridge, and used 10-round en bloc clips. Twenty samples of each were made and sent out to infantry and cavalry units for field testing.
This rifle is one of those Garands - serial number 15, to be specific. The results of the trial was a preference for the Garand rifle, and the testing board got as far as writing a formal recommendation for its adoption before General MacArthur vetoed the whole .276 caliber idea for economic and logistical reasons (the US Army had a whole lot of .30-06 ammo and not a lot of spare cash). The result was ultimately a .30 caliber Garand rifle becoming the M1, but this T3E2 trials rifle in .276 sure is a sweet-handling piece of machinery!