Here is a link to a YouTube video that might shine some light on the seemingly never ending argument surrounding Bi-metal russian 223 ammo and premature barrel wear. In the video they actually test and determine the hardness of bi-metal bullets, standard copper clad lead and the hardness of a supposid Mil-spec AR-15 barrel.
https://www.youtube.com/watch?v=IWwmAMVh8Qs

I felt some who shoot a lot of the Russian 223 loaded with Bi-metal bullets or are considering it, might find it of value.