"Wrong. I have shot 1/4 inch plate at 25 yards with an ar15 and my ak. The ak goes through, the 223 dents it with maybe a one or two millimeter hole."
Here's the difference for me. The .223 was copper jacket and went right through the mild plate. The .30 cal was a hunting round. I suppose if it was copper jacket also it would have went through but instead it made a large round dent.
the 223 was a M193 55 gr FMJ
the 7.62X39 was a wolf 123 gr FMJ