Yes. These were made for one purpose...to go 'full regalia' into a war effort. Just like an M1, they are tools that were tried & trued for one job. Would be silly for them yo not be interchangeable.
They were designed to be repaired and replaced with the other parts available. Thats one of the reasons why I (contrary to most ppl) actually dont mind lowers and uppers not matching on war time guns. Its in their very nature to not match. Its almost a sign that it did its job in a weird way. The US Army ordnance didnt care and the soldier firing it didnt care...so why should I! haha