They really have come a very long way since the WW II era steel pots you and I used to wear Keith. Kevlar was a great improvement I thought, but they have continued to develop new technology and now they have apparently settled on one for general issue that can defeat a direct strike from a long rifle round.
http://www.strategypage.com/htmw/htinf/articles/20090901.aspxDe Oppresso Liber