Holy cow, you guys are good!

There is the matching serial number on the barrel, covered up by the latch. And there is the matching serial number on the inside of the right grip! It is even harder to see than the example Handejector posted. I had to hold it by a lamp and hold the grip at an angle to see it. It's just barely scratched on it.

As for the serial number on the butt, it is offset so the swivel does not interfere with it.