The Lee dies have stops to prevent camover. I don't think the aluminum can handle that much leverage safely.
jersurf101,
Three possibilities:
First, when the errant case is up in the die, look sideways at the press to see if there's a crack of light between the shell holder and the die. You just need enough force to close that gap. Lee recommends ΒΌ turn beyond contact as a starting point, but check. You can watch the fellow in the
Lee help video demonstrate this.
Second, run the cases up into the die three times, as mentioned, but turn the case about a third of a turn in the holder each time and hold them up in the die for a count of five each time to let the metal lose a little bit of its spring. I can almost always get at least two more thousandths off a shoulder this way. That may be enough, depending on your chamber.
Third, if that last method doesn't get you enough shoulder setback, follow Mr. Guffey's point on using a feeler gauge. To do this you will need to use wrenches to loosen the decapper rod from in the die so you can remove it. Then, when sizing each case, slip a 0.005" automotive feeler gauge into the mouth of the shell holder just under the head (bottom) of the case in the shell holder. That will force the case up an additional 0.005", driving it that much deeper into the sizing die. This will lengthen the cases by squeezing more shoulder metal up into the neck, so check for need to trim afterward.
The last to items may seem like a lot of extra work, but remember you only have to do this once. The cases won't give you this problem after being fired in your chamber.