Ok I like preforms and I learned something new today about flakes passing center during paloflaking. This is advance, advance, stuff or maybe I am just a slow learner. But once you're done you're done. The convex , hollow ground surface presents an upward obstacle to center passing flakes or extra mass can as well cause this. I have seen a solution with an Anvil stone and now believe this to not be the solution....just a thought and I need a couple more preforms to have a working theory for everyone. But I think I have just about solved it. What this could mean is no more rounding off the otherside of nice preforms that cause us to always reshape