Just took a couple of photos to try to show the 'fractures' around the ogive of my Hornady 270gr RN bullets. This one shows it up fairly well:

BTW, I think that is what is visible inside the jackets of the sectioned Hornadys in Daryl's earlier post. They would certainly aid in quick opening at the lower velocities we're talking about here. Time to test the theory on our local bovines, if only this damn rain would stop!