resizing live ammo???
If I understand you correctly.......Resizing live ammo...If it is possible...May cause some extremely excessive pressures. Was this ammo fire formed for another firearm, and neck sized only? If so it probably would give you problems chambering. It may be that the shoulder just needs to be bumped a bit. I would suggest pulling the bullets, disposing of the powder (unless you're positive of the age and type), FL size one or two of the cases, reload with a charge and pill that you are sure of...and see if you still have the same problem. If so...file 13 the whole lot. Or turn the necks and try again.
The Roman Empire was not built nor did it prosper and come to be feared by all the land by doing paperwork or having meetings....It accomplished this by killing all that opposed it!
There are no "stupid questions"...There are, however... Alot of "inquisitive idiots!"