ha! - Well done oldcolonel.

If the Colonel's #'s are even remotely correct, then the problem is in the dies (expander plug).

If the expander plug is over about .424" or .425", it's oversized and is opening the cases up too large so they cannot possibly hold a bullet properly.

Colonel - you've noted above that the expander plug is .435" - that's .011" ( 11 thousandths ) larger than it should be.

That is why Mike suggested you try sizing the brass without the expander plug and check bullet fit. It could be your dies are properly sizing the brass, but the oversize expander plug is opening them too much.