Some jacketed benchrest shooters have been using a "bore rider" throat. Instead of the typical 1.5 degree per side leade angle, the first half of the leade is 0.5 degree per side and the final half is 1.5 degree per side.
Why not simply use 0.5 degree all the way? Well, that would make the leade longer which is not necessarily a good thing. I guess the theory is that the 0.5 degree beginning does a better job of aligning the bullet, while the 1.5 degree finish keeps the lead from being excessively long.