The bullet has stretched a little. I can tell what used to be what by the knurled around the bearing surface. And it’s elongated but is present all the way around the bullet. One side is disproportionately reduced and it almost looks like a D viewed from the base. There is significant gap when placed in a sized case, presumably from the stretching action Weight went from 200 gr to 141 grains in the process. I agree it doesn’t go with any of my models except maybe a bum bullet. Maybe if there was a big enough defect on the base? I loaded these on a lee turret and gave them all some QC attention not saying I’m perfect but still... thanks for the input! Mysterious indeed!