I think.
It is not your case length. Max is 1.760 and "Trim-to" is 1.750, anything in between 1.750 and 1.760 will be fine.
I think we need a little more information.
How did you set up your FL sizing die? The generic way is to raise the ram, screw the die into the press until it touches the shell holder, lower the ram and screw the die in 1/4 turn more.
Have you tried to chamber just the sized brass, no bullet? This will tell you if it's your "messed up" expander ball or not. If you have and they chamber with ease, then you know it's in your seating process.
I think this is what is wrong,
. Are you seating and crimping with the same die in the same step? Over crimping with the seating die can bulge/deform the necks so they will not chamber.
Back the seating die out of the press so as to remove the crimp feature and load a few rounds. My guess is they will chamber with ease.