Full auto has been a doctrinal no-no since the mid 1940s for riflemen. It's just a waste of ammunition in 99/100 cases. That became even more pronounced as intermediate cartridges and assault rifles like the STG-44 and AK-47 eliminated the need for Submachineguns. The United States was basically just stuck on full-powered rifle cartridges for service use because the M1 Garand won us tha bigg'un. The Germans basically made them obsolete with 7.92x39mm and later the Russians with 7.62x39mm. There was actually a really strong push for an intermediate in NATO in the form of .280 British but the United States shot it down on the basis of basicly it not looking like .30-06 like 7.62x51mm did, which was the American idea of an intermediate at the time.