I posted a few questions about 5.56x45mm NATO vs .223 Rem.
I gathered in that thread that there are advantages to going with a 5.56x45mm NATO firearm as it will safely fire both 5.56x45mm NATO and .223 Rem safely. The problem, unlike .38 Spl vs .357 Mag, where the more powerful .357 Mag will not fit into a .38 Spl firearm, the 5.56x45mm NATO will fit and fire in a .223 Rem chambered firearm. The common wisdom, there is a safety issue using the more powerful 5.56x45mm NATO in a .223 Rem chambered firearm.
Now I have a similiar question concerning the 7.62x51mm NATO vs .308 Win. I've been told they are safely interchangeable. Then I read that they are not, and unlike a .223 in a 5.56x45mm firearm, a .308 Win is not safe to fire in a 7.62x51mm firearm, in addition, a 7.62x51mm should not be fired in a .308 Win firearm.
In addition, something about a summary from the link confused me. Can anyone clarify this for me:
"The worst case scenario for shooters of 7.62 NATO rifles is as follows: Using a commercially made, maximum pressure cartridge with long headspace, fired from a weak action (ex. converted 93/95 Mausers)."
"The weaker action is a possible final piece of the 308 vs 7.62 NATO puzzle."