Point taken on the M1/M14 issue. I do agree that an even-handed argument about the supposed superiority of the AK design is possible. I'm not the person for it. However, there are many reasons for replacing a rifle in the midst of a war. Especially a war that seemingly had little direct effect on national security. A small scale(relatively, of course) conflict like Vietnam may only have had an indirect bearing on the small arms development process. Cost of the rifle and ammunition, ease of manufacture, weight, and other myriad factors can just as easily be cited for the replacement of the M14. It could be suggested as a possibility but it might be better to relegate that to the M14 and M16 pages. I still stand by my assertion that the AR line of rifles was not directly made in response to the AK-47, at least not in an easily shown manner. The United States Army Continental Army Command (CONARC) sponsored development of a light weight, .22 caliber rifle in 1957. This was done in light of a Operations Research Office's(ORO) report on casualties, distances, etc.(http://www.ar15.com/content/articles/history/birth.html) It seems to me that the AR-15 was a natural evolution of those ideas, using an operating system originally developed to compete with the M14. 
 : I'm glad to chat with you and hope that discussions like these can help to edify and enlighten.