French Canadian-born Garand went to work at the United States Army's Springfield Armory and began working on a .30 caliber primer actuated blowback Model 1919 prototype. In 1924, twenty-four rifles, identified as "M1922s", were built at Springfield. At Fort Benning during 1925, they were tested against models by Berthier, Hatcher-Bang, Thompson, and Pedersen, the latter two being delayed blowback types. This led to a further trial of an improved "M1924" Garand against the Thompson, ultimately producing an inconclusive report. As a result, the Ordnance Board ordered a .30-06 Garand variant. In March 1927, the cavalry board reported trials among the Thompson, Garand, and 03 Springfield had not led to a clear winner. This led to a gas-operated .276 (7 mm) model (patented by Garand on 12 April 1930).

In early 1928, both the infantry and cavalry boards ran trials with the .276 Pedersen T1 rifle, calling it "highly promising" (despite its use of waxed ammunition, shared by the Thompson). On 13 August 1928, a semiautomatic rifle board (SRB) carried out joint Army, Navy, and Marine Corps trials between the .30 Thompson, both cavalry and infantry versions of the T1 Pedersen, "M1924" Garand, and .256 Bang, and on 21 September, the board reported no clear winner. The .30 Garand, however, was dropped in favor of the .276.

https://en.wikipedia.org/wiki/M1_Garand

M1 Garand: full disassembly & assembly
https://www.youtube.com/watch?v=MzayGnfEZi8

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