Boolit being sized when seated.
I am trying to reload 124 gr TC boolits cast with a lee mold. I cast the boolits out of pure lead with some tin. When I seat the bullets which drop at an average of .358 they become sized all the way down to .353. I'm using a lee seating die which came with my 4 die set, and am not using the post sizing die. I have pulled many boolits after seating them with the die being screwed in the recomended way as well as unscrewed as far as possible and the boolits are still being sized down to .353. Is this because I am using only lead and it is not hard enough, or is the problem with the seating die. Any input would be appreciated.