I was big on Dong behind the buffer or the old double spring. Actually the M-60 performed best when left alone. I remember stealing shit just to get receiver groups for the things, parts, especially barrels were very hard to come by. I remember several occasions where my souped up 60 failed me and finally just used original parts. Remember the feed trays, those aluminum contraptions that were supposed to facilitate the feed...Huh Uh! The old B-3 can was just fine thank you very much. With the 101st I got a mini mounted in the door, now that was supressive fire.