Thanks Kernalvax. Question #1 answered.
Any takers on Question #2. The internet has mostly confirmed a rifle chambered in .308 can take NATO 7.62x51mm. Apparently it is not 100% safe to do the opposite. That said, the internet doesn't offer to pull bits of my rifle out of my face if things go wrong.
Many posts state that the rifles chambered in 7.62x51mm often have extra head space to allow for ammunition inconsistencies. Also that the thicker military brass avoids nasty results when the gaps occur due to this extra head space. Place a reloaded, commercial, thinner cased .308 in these chambers and you may, in rare cases, get a nasty surprise. Is this the case CGN?
Sorry this is slightly off topic John, but I'm hoping to have this answered so when you get surplus 7.62x51mm in all the M14s newbies can confidently order up all your ammo.