I've never understood why someone would want to have a completely flat tip on their break cue. Yeah sure you might get less spin. But if you hit anywhere off center it would just make you miscue instead of getting unintended spin.
Another guy I know has a phenolic on his break cue and he doesn't even chalk it! He says there's no need for chalk since he is hitting center ball. That's a recipe for a miscue if you ask me.
I use a nickel/quarter radius. Quarter is probably perfect for 9 ball, but I like to be able to use the same tip for 2nd ball 8 ball break, too (in case that's what seems to work), and quarter is a tad flat for that.
> Mine is shaped to a 13mm wide piece of a 1 1/8 radius,which is half of a 2 1/4 ball. It LOOKS flat to some people,but gives you the biggest possible sweet spot.
On a break where I've really pounded them and squatted it,the chalk mark left on the ball is the full width of my tip. Tommy D.