It does look like my Euroarms. On mine it has markings on the other side of the barrel, and it should have proof marks and a date code on the other side of the frame. Can you take pics of the other side?
No exposed barrel threads at the rear of the barrel like the early Remingtons. All other '58 repros have exposed threads. Look for faint markings under the barrel above the loading lever. Quite possible a small circle with DGG in it. It's possible it was a kit gun and the markings were lost when it was finished. Yes, ASP kit guns were marked, I have one that was built by someone.
Sometimes that DGG mark is encircled, sometimes not, The one I have is very faint, not circled and is stacked almost on top of each other. Almost got to have an micro scope to see it. Under loading leaver, right up against the barrel..