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Let's say Chinese paper armor becomes commonplace some time in the 1400's. Most nations fielding guns also field the armor and spend the years since working to perfect the armor with tech appropriate to each era. Does this butterfly away the existence of intermediate rounds in the 1900's? Would a mid to late 1900's where everyone has effective body armor cause automatic rifles and machine guns to skew towards high energy rounds perhaps like the M14's cartridges? Would intermediate rounds still dominate the battlefield?