That is sooooooooo not right....... Mine measure .360" top to bottom. I don't know the dies your using but either your expander has lousy taper or your lube aint cutting it. I have done this allot and have never sean that. Do the dies your using have a smooth tapered expander? I don't use lee dies so I don't know them. I have seen Rcbs and redding expanders that were not tapered very well for this type of operation.
The expander should hang down toward the bottom of the die but still inside the die as usual. Just need to be sure you are sizing inside of the neck on the way up outside at the top of the stroke and inside again on the way out like normal.
When I was thinking about an edge I talked to die maker, I think he was in Iowa said he could take my 300 ultra FL sizer die and ream the neck install a 338 bushing and expander turn it into an edge..and he was very reasonable on price....wish I could remember his name..