R.Marshall
It looks like a nice drilling, in spite of the fact that I am a 16 ga. man. It would be helpful if you post additional photos. You should post photos of all the markings, especially the proof marks. To find these, you need to remove the forearm and barrels. The proof marks will be found under the barrels. Also an overall photo would be helpful, because there are several different rifle barrel selectors and we can't tell whether yours is the common type, or something else.
Mike