I recall what 7.62mm did & 5.56mm didn't in war. What conditions would the 6.8mm in NGSW-R & NGSW-AR not be ideal?
We already have the 7.62, guns & ammo.
Maybe you have your wars for 7.62 & 5.56 but I'm not going there as a senior citizen. <<>> President Obama had Seal Team Six. President "W" rewarded his Secret Service protection with free pizza recently. I guess he didn't want extra ammo and guns either..