FAL phil, CMP is listing surplus barreled Navy actions and sell just about any part you would need to get them up and running. the special grades are indeed criterion barrels with mostly new parts. if the rifles indeed function properly I would say that they would be a great bargain over an M1a or norinko M14 knockoff.
however I would say that retired members, no matter whether they have been recalled or volunteered, would be placed in support roles, not combat roles. you would be the ones manning the mess halls, sitting behind desks and and supply tasks that could be handled by LLD personell. also in the event that there was crippling shortages of weapons to issue, a 308 would probably be pretty hard to feed for most bases, I know on my carrier we had M14s for drilling, shark watches, and anything that 5.56 couldn't handle but 50 cal was overkill for but we had very limited supplies of ammo for them. an AR15 or other evil black rifle would be much more practical to supplement existing stores as you would use the same ammo as everyone else and if your rifle broke USGI parts are interchangeable, if the trigger group broke then you will have hit the jackpot(three round burst, here we come
EDIT: thank you for your service!