Gee!
I have heard of some other folks who do the same things. But in general PUSHING the expander ball (if it's straight) into the neck results in straighter necks. This is because the bottom of the case is supported by the bottom of the shell-holder.
All of which is why I test every new set of "conventional" sizing dies (whether neck or full-length) to see how they do before loading any batch of ammo.
Sometimes they make straight cases right out of the box. If not, I use various techniques to fix 'em.
Must also note that have encountered more than one sizing die over the decades that was defective, due to the neck portion being out-of-line with the body....
