LRB Arms, NY.
They are the only ones now producing a Forged M14 Receiver just like the originals. I hear they now have a few month back order for their receivers. Most guys collect USGI parts from all over, buy a LRB or another Non Forged Receiver and have a smith put it together. From what I understand assembling a M14 is not for the novice.
http://www.lrbarms.com