Richard V6. That is what I believe has been done. The Caliper is ally. (2011 car) & I guess the nipple is steel. Don’t want to wreck the Caliper as new ones are slightly different, which means 2. Trouble is each are north of £600.
I suspect the nipple seat is damaged, but trying a new nipple might work. If not a new insert may work.
Inserts
