My EJN 757 is built on a commercial Mauser action, which makes me believe that it's probably not a Mossberg. I have been told that it was manufactured by FN for Monkey Wards, and it is identical to photos of older FN's that I have seen.
Like some of the other posters, mine is no looker, with ugly wood, poor checkering, terrible wood to metal fit and a finish that ranges from deep blue to a plummy grey. However, it is the most accurate rifle that I own, more so than my Cooper .308.
Every year, I take it for it's annual mid October range trip. I love laying it down next to the $1000 plus rigs on either side and putting three shots inside of a quarter at 200 yards. "I guess it's zeroed" generally gets pretty nasty looks from most of the rest of the shooters on the line.