I would find the rings year. You may have that. Find where, what Group, Battalion, Company,Squad and you have returned that ring my friend. Congratulations
Not sure how old the ring is but the numbers could be the last four of his Social Security Number. I've never seen that done before but that is my guess. There are some folks on here who are really good at this kind of research. Hopefully they can help you out.
It has the “Shell and Flame” of the U.S. Army Ordnance Branch. Oldest branch symbol and is still used today. If the numbers are last 4 of SSN that would put it later than 1974. Best clue might be the makers mark. These rings were very popular and sold everywhere to military members, advertised in the Army Times and Stars and Stripes into the 90’s. They were marketed towards those who didn’t have a high school ring as a non HS grad or couldn’t afford one. Do I see U.S. ARMY EUROPE? If so it’s most likely a Cold War reference...1960’s up to the 90’s.
Nice find.