It depends
The links below discuss the differences between the .308 Win. and 7.62mm NATO. The second link talks about the .223 Rem and the 5.56mm and some potential concerns. Interesting reading so you can draw your own conclusions. Hope this helps. All the best...
Gil
http://www.thegunzone.com/30cal.html
http://www.thegunzone.com/556v223.html
The links below discuss the differences between the .308 Win. and 7.62mm NATO. The second link talks about the .223 Rem and the 5.56mm and some potential concerns. Interesting reading so you can draw your own conclusions. Hope this helps. All the best...
Gil
http://www.thegunzone.com/30cal.html
http://www.thegunzone.com/556v223.html