You're good to go , test a few rounds and look for signs of over pressure , elevated chamber pressures are revealed by overly flattened primers or by powder stains around the primer that reveal leaking gasses , also if the bolt seems harder to work , if none of that happens , fire away .
You're more likely to have a issue with a out of spec round of ammo , be it .223rem or 5.56 NATO , then you are using 5.56 in a .223 , A bad round is a bad round .