The Air Force bags are good equipment, and will keep you warm probably down to about 20 degrees. Thats a nice warm sleep, they will probably keep you alive much lower than this, maybe 0 or even -10, but you will not be sleeping much. Alot depends on your physical state, and how much you have had to eat. I would guess that the bag I unpacked regained about 50% of its orginal loft, and it had been packed for about 14 months. I was told that even after being compressed for several years it would re-loft to this 50% level

Speaking of surplus stores and sleeping bags. Earlier this year I picked up a fairly new Modular Sleeping System at the local army store. Green patrol bag, black intermediate bag, Gore-tex bivy cover, and compression sack. The price? a slick $125 Now thats a deal :-)