Once baked.......it is done. I do not think baking for any longer will do anything. I have never had your problem! You can add more powder and bake that 2nd layer, but the 1st layer is done.
I think you may have a sizing problem. PC is not a cure-all for everything. Do you know your slugged size?
I bake ALL my powders ONLY 10 min @400F. All work....no leading.
Hope you locate your problem. I really do not think it is the PC, as thousands of us use it on a regualr basis with NO leading at all.
GOOD LUCK!
banger-j