for a 308win savage you can swap the barrel for any of the 'family' with the same mag as well, ie, no other mods, 243win/260rem/7mm-o8/338Fed/358win and any other rounds with a similar bolt head + body shape + overall length.

for the 223Rem; you should be ok for swapping to 222Rem/17Rem/204Rug/222RemMag and a few others too...