I once had a 12 ga Daly 500 with a 400,000+ serial number; way higher than the Dalys. It didn't have the 500 banner like Daly 500s do on the side of the receiver, but one of the barrels was roll stamped Daly 500.

Through looking around, I found that that high of a number was the regular Miroku 500 gun. One can only imagine what the story is behind that gun.