User blog comment:Deadliest Issue/Skynet Vs Omnicorp/@comment-5795750-20140313073101/@comment-5795750-20140314004254

"Armor-piercing rounds"... the endoskeleton of a Terminator doesn't really count as armor... maybe when Omnicorp were developing said rounds, they were using those rounds to counter against armour that could be worn by humans i.e. kevlar vests, and not robotic beings; granted the Terminator does have its weak points but they are hard to spot

As for the "what was the strongest object the plasma rifles pierced" question: the plasma rifles were used against the Terminators themselves so the endoskeleton of a Terminator itself was the strongest object those rifles pierced (although it had to be wielded by a human)