As for your already loaded brass. I would just pull the bullets, remove the decap pin from the sizer (Leave the expander ball) and resize the brass and load em up again.
I had to give this advice to a friend just yesterday after he told me he reloaded 300 .223's and afterwards found out they wouldn't fit into his chamber. . When I asked him if he performed a "plunk" test while reloading them, he simply asked "what's that?".