As has been stated, if you're over crimping, you can create a problem, and trying to crimp more will just exacerbate it. That said, if you have already over crimped these rounds and still want to shoot them, go buy a Lee Factory Crimp die. Adjust the die according to the directions, then run these potentially over crimped rounds through it. It should fix your problem even if you've over crimped them.
When flaring cases, you don't need to flare to the point that the bullet slides way down into the case. You want to flare just enough to allow the base of the bullet to start. This means you'll have to flare a little bit more with lead bullets than jacketed bullets, but it shouldn't be much more.