Culit,
You indicated the chamber length is 70mm, the 16 in a circle shows it was proofed with 65mm chambers. If the chambers actually measure 70mm, they were likely lengthened in the US and not reproofed. The engraving, in my opinion, was by special request and maybe used a photo of the owner's favorite hunting dogs. I'm not sure the dogs are dachshunds; they could also be shorthair or wirehair pointers.
Mike