Infor on the 5.56 Special Purpose AP

I recently acquired this round and wanted to know more about it. I was told it is basically solid steel and damages the barrel. So why make this round, what are it’s benefits etc.
Thanks … sort=3&o=0

American Ballistics made a number of variations of steel bullets in this & other case types (9 Para, .308 & ??). I haven’t yet talked to anyone or read anywhere what other than AP these were to accomplish. Yes they must be wonderful at barrel wear.

They did make some bullets of other materials and designs. None it seems caught on.

Discussion involving some other cartridges by American Ballistics: viewtopic.php?f=8&t=16082

I have seen a 9mm luger load that was shot into a steel sheet in a test. The tip of the bullet just slightly penetrated the 1/4" sheet but the chamber pressure was very high so it is a very hot load. I have no idea on the 5.56mm.