Expanding Pistol Cases for cast bullets & Brass 'SPRING-BACK'

How much do we actually move or re-shape our pistol brass when sizing and expanding? Does 'used' brass actually take the expander mandrel size or does it want to spring back to the pre-'sized' inside diameter from being reloaded many times and getting 'work hardened'?
I'm trying to get a dialogue started about what we think we are doing/achieving when we expand our brass for soft cast projectiles. If the case is not expanded enough, it will try to swage our projectiles, especially in stowage over time.
We do all we can to get a proper cast bullet fit to our barrels, they say fit is 'king' and fit is just one of the variables to prevent barrel leading. On the other side of the coin...if our cases further swage our projectiles after seating then we unknowingly are defeating our best efforts.
I think that a case that's .001"~.002" smaller on the inside diameter along with a proper crimp will hold any cast bullet, provide 'start pressure' and prevent it from being seated deeper when loaded in a tubular magazine or from recoil. I will start a post over at slack Reloaders Network and we can talk about it some...
If your not a member, please come over and join us...please forgive the video quality as I am no videographer by a long shot, I'm just an old BrassStuffer using an old iPhone 4 !
Hope to see some of your new faces over at the 'SLACK RELOADERS NETWORK" created for Handloaders & Casters, 'Content Providers' & Viewers of like minds.

Thank you for watching and commenting...'CharlieBrassStuffer'