Is this a 3/4 in. regulator, or a 1-in. regulator?
I don't see any indication that the pressure reducing valve is a different size than the pipe. What part do you think is the threaded adapter? If the pipe is 3/4 and the home was built this year I don't see why they would've used a 1" PRV with adapters.

Can you find a part number on the PRV anywhere?