I'm glad I found this site. Wish I had found it before I spent that last $1000 on the Ar-15. I trained on an M-14, yes, I'm somewhat antique also. I grew up with a Springfield so was used to the recoil. Never shot the 5.56mm and thought it would at least continue to have access to ammunition. For the time it was deployed it made sense to the people in charge. The system's great but I didn't much like the impact results. Too many of the guys coming back from Vietnam talked about carrying the confiscated AKs because of lack of knockdown power.
Guys in Afghanistan talk about needing long range, high angle capabilities. The 7.62mm with a 24 inch barrel will do that. Won't need another caliber, the M-134 still uses 7.62mm rounds I think.
Wish we had started with A-10s. Could change uppers, magazines and be good to go!