The German machine gun, the MG42, fired at twice the speed of its counterparts, was nicknamed “Hitler’s Buzzsaw”, and the U.S. Army even created training films to help soldiers cope with the trauma of facing the weapon in combat.
The official US position during WW2 was that the 42 wasted ammunition compared to the American equivalent- the 30 calibre Browning.
But in fact, the brass recognized that it was a superior weapon, and an engineering team was set to work in 1943 to reverse engineer the 42 for American use.
Unfortunately the project failed because they couldn’t get the copy to work with the standard American 30 cal ammunition- something about the Mauser ammunition having a rim the American didn’t, or the .30 being too short- the American guns just jammed after a few hundred rounds. So the project was quietly shelved.