A US Marine/Army Great War veteran, operating against guerrillas in Nicaragua/Dominican Republic/or similar, remembers seeing a full-auto variant of a Model 1907 in the French trenches. He requests info from Winchester through channels. Winchester graciously offers a half dozen new Model 1907 automatics with extended magazines and bayonet lugs for testing. Reports up the pipeline praise the rifle. Several problems are noted. However, the round has greater range than the .45 ACP and is flatter shooting. The rifle is lighter. A panel is designated to adapt the gun and cartridge to meet military standards with development by Winchester. This panel quickly demands a simpler break down procedure, a .30 caliber variant of the cartridge using a 150 grain spire point, and a cocking handle on the bolt. In 1927, the US Army adopts the weapon as a submachine carbine to augment the Thompson. A program is started in 1935 to reduce the weight to less than six pounds to use as a pistol replacement for rear echelon troops.
At this point you have a gun/cartridge combo which has similar power to a .30-30 carbine.