Sorry, got my posters mixed up.
But, I don't think you could have a controllable full auto .30-'06 without that weight.
Why not? He could bring more fire to bear quicker than anyone in the squad.
I understand, the BAR wasn't a perfect weapon, but until the assult rifle came along, the BAR was one of the best options available for putting portable automatic fire in the hands of an infantry squad.
Michael