>>599733>Made of a poly-laminate composite, the outer shell of the T-51b is lightweight and capable of absorbing over 2500 Joules of kinetic impact..223 has around 1800 J of energy, so it could reasonably perforate joints and other weak points.
.308 has around 3500 J of energy, so it could possibly perforate the armor itself.
>power armor could take on mini nukes with minimal damage, direct tank shells to the face and walk away,[Citation Needed]