We were issued M-14's when I went to Vietnam in 1965,but my outfit,3rd Reconnaissance battalion, was pretty lenient about what you could carry as long as you could get ammunition for it. One of our platoon leaders carried a ak-47 another a Swedish K and one had an m-16 that he had obtained in a trade somewhere. This was before the marines were issued any m-16's.I liked the penetration of the 308 bullet as opposed to the .223. I suppose every advantage has a corresponding downside,but I want something that will penetrate more than I was concerned about weight.I was the radio operator and I carried 80 pounds plus,verified weight,when I was on patrol. i weighed 165 pounds then and did not know what being tired was when not actually on patrol,I was in outstanding shape as I had to be.I really like the M-14 and bought a Springfield M1A when they came out.