Surprised me too.
Soft lead alloys size true to the sizer.
Hard lead alloys besides being bigger in diameter as cast,
size to about 0.001" bigger than the sizer die nominal.
I have both Lee and CH4D sizing dies that are supposed to be 0.460" diameter, and I believe they both are.
Copper jacket with soft lead core will spring back about 0.002".
Monometal copper and monometal brass do same or a little more, maybe 0.0025".
