Lake City brass, if is not new, unfired brass, will have crimped primers, and those crimps don't come out completely with the primer. You have to cut the old crimp out. Some commercial brass also has crimped pockets. Some primers, like TulAmmo and Wolf are also a little fatter than others. If you just need to remove crimps, there have been recent posts on the tools and methods for doing it that you can search for. If you are using the slightly fat primers, though, the solution is likely going to be to use a primer pocket reamer or a a primer pocket swaging tool to loosen the pockets a little.
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