Dave,
The clay in my yard is so hard that during dry spells its hard to drive a stake into it. I tried to auger some holes during one of those dry spells and could not even get the cast auger tip to penetrate. (nevermind the sheeetmetal helixes- it never penetrated far enough for them to engage) Once those helixes engage, I think they help suck the auger into the ground by virtue of their geometry. Its just that on mine, they would need to overcome the flotation of that small, bullet nosed tip. No one would every think about designing a drill like that tip unless they were drilling mud. Next time, I'll grind some grooves in the tip so that it will cut to center. And like any drill or cutter- relieve it behind the cutting edge.
John