Here is a new idea. Sit a tip under one of those automatic power hammers for a day or two. Trim it to shape every so often, and repeat. (is that what you are talking about with impact?)
I notice on new tips, I can go weeks reshaping it to my desired radius, never removing anything from the center of the tip. I can't believe the amount of compression you get pushing a little white ball around.
While I'm thinking about it, would there be a noticeable difference between a pressed tip where it is harder everywhere, and a broken in tip where all of the compression is in the center?