I was one of the guys who lugged the 11. something pound M-14 over hill and dale in our 10 year adventure in beautiful Vietnam. Although it wasn't perfect, and I used a "LOT" of luberplate. I always like the 7.62x51 cartridge. The M-16 with it's 5.56x45 was not introduced until after I had departed the scene. It is my understanding that the Army received them much earlier than the Marines. I was informed that at one point the weapons were changed out as such."Gimme that M-14 ! Here take this M-16" and off we go.I can't say that for a fact but that's how I got it from a buddy who was there. Here is the thought that has run through my mind for many years. Knowing how the 7.62x51 (how can I say this with tact?) reacted to contact with a persons body. What in fact was the difference (if any) with the 5.56x45.Again, I was informed by guys who were there that they saw people take up to 5 hits with the 5.56x45.If anyone has reliable info I would appreciate some feed back. Not hearsay?