Ive always wondered about this.I was with Marines. HQ 2-11 ,an artillery battalion in 66&67. We were in support of 5th Marines , an infantry Battalion. We were issued M-14s.It was that way when I went home.It's my understanding that somewhere down the line.M-16s were unceremoniously issued to the Marines.Gimme your M-14,Heres you M-16.I find this hard to believe.I know if I went from the 762 to the 223.I would have been in shock.No training or familiarization. I know we used to get all the hand me downs.But doing that in a combat sounds strange.Well,it was all strange I guess.Any grunts out there know anything ?