Missing witness mark

[Steve D]

As additional information, I have attached two photos of 42 Code pistols that I have always wondered about. In the second, the mark on the barrel appears to have been made by a more blunt tool than that on the receiver. I know the barrel is slightly larger than the receiver and the mark may simply be struck deeper on the barrel, but on close inspection, I believe they were not made at the same time or with the same tool as has been discussed. In the first photo, the witness mark on the barrel is missing. I had always assumed a replacement barrel, but now, maybe not.