Definitely an odd deal.
If it had expanded even slightly and tumbled I suspect the First Lite crew would have noticed and made that remark, and I'd suspect the base would be bent or divoted due to hitting bone or whatever it was that made the bullet tumble, though you can only see one side of the bullet. The rifling mark looks legit to me, but I didn't blow it up and that's only a cursory glance at it. With deep lands I could see rifling marks being on the very beginning of the boattail like the pic shows, but again that's only from a cursory glance at it.
The bullet does look suspiciously new and shiny but I've recovered bullets without obvious burn residue on the base before. It isn't unheard of.
