I couldn't figure out why my flat base .223 bullets were coming out with tip damage. I had a good chamfer on my case necks and was careful to line up the bullet before seating. After a quick Google search I found that I wasn't the only one. Here's how I fixed the problem:
Picture of damaged vmax tip still wedged in RCBS FL Seater Die.
Dremel bit and sacrificial sp polishing bullet. The Dremel was used to put a slight chamfer in the sharp inside edge of the seater. I was careful to not alter the actual seating surface.
Seater chucked in drill. Used plain old brass polish to smooth out dremel chamfer. Flitz would have made quick work of it.
Finished product. Now all bullets go in and seat well even if they are seriously tipped to one side going in. As long as you get it started and your finger out of the way the bullets seat nicely. I also backed the seater off a little. I you dreaded flat base bullets, try this and you'll be amazed at how easy they seat.