Adept posted a video showing how the NovaSteel Helmet holds up to this endurance test that can reflect real world conditions... "When it comes to durability, one helmet stands head and shoulders above the pack, and this is something we wanted to demonstrate.  So we took a few helmets down to the range, together with a .357 Magnum revolver firing FPJ ammo from PPU.

The first helmet, a Czech M53, was penetrated almost instantly.  This highlights the shortcomings of 20th century steel helmets.

The second helmet, a police surplus helmet ostensibly rated IIIA, took a few shots, but with severe degradation and extreme localized deformation -- almost penciling.  

The NovaSteel ACH-style helmet took more than two dozen shots, and could have taken many more.  Shots were stacked, bolts were hit, bullets impacted right on the edge -- but the helmet pulled through without a single penetration, with very limited shell deformation, and with pads still in good shape.  Had to stop when the retention system couldn't take further punishment -- if we had a spare on hand, we probably could have put two dozen more shots onto that shell."