I know you weren't Jaycee. You're correct, he never thought the thread might be other than SAE and didn't check. Swapped it out, never hunted/shot it again and had to sell due to a pregnant wife.
Seems it was a "FIE" from Italy or something. Everyone just has to be extremely careful, especially on a preowned or BP firearm. I thought I had done due diligence but was hurt anyway.