MY COMMENT: 7.62mm NATO makes more sense than .223/5.56mm for civilian 2A Militia. Non-vets don't have the training or discipline to take battlefield advantage of the "assault rifle" characteristics. In a deep Militia situation, they will be doing fire-support, set-position defense, and logistics--NOT fire-and-maneuver assaults.
Add in the political factor: .308 is less conducive to "assault"-type situations. A featureless rifle in .308 has far reduced "assaultive" characteristics (.223/5.56 has become innately associated with mass shootings), as well as higher "sporting" use (as cover). All this can help protect such a weapon from AW-type bans if played right. 2A is not about hobbies or preferences. It's about preserving firepower. And should mag limits be implemented, ten rounds of 7.62 beats ten rounds of 5.56. Personal battle rifle picks: A NY-compliant M14 due to familiarity of many, or a .308 AK pattern due to maintenance issues in them being held by non-vet civilians not under military authority and discipline.(NOTE: The guy does drink a bit.)