I've been trying these on and off for months now, and have yet to successfully use a flat top punch in my Lyman 450. They are the second quickest way to destroy a bullet, clearly not as foolproof as so many will have me believe. The whole idea is that the flat punch can self-center on a flat nose bullet, right? That is not happening for me, and it is sizing bullets crooked. With the proper top punch, they come out as perfect as I can tell. so it's not the press or die.
Attachment 224250
I'm not sure if it's clear in this picture, but near the top, there is a bullet that you can see on one side the top band looks ok, but the other is washed almost completely off. I've tried making my own flat top punches, and the pictured bullets were with an Accurate molds flat top punch. I've tried polishing with 2000 grit sandpaper, and lubing with various oils. As soon as the bullet hits the sizing die, there is too much downward pressure on the nose for it to self-center. Again, with a fitted top punch that supports the nose, I do not notice this problem. I've tried with bullets with a nose as wide as .310", and as small as .18". No difference. I like the idea of a flat top punch, so how do you guys make them work?