Sorry I can't be of much help.. I can say what it isn't.
Though what you have looks a lot like a S&W Safety Hammerless Mod 4 as it has a pinned front sight, the trigger on what you have is not even close, so that rules the S&W line out and also rules out an Ivar Johnson(though the trigger on an I-J is closer to what you have).
The S&W models would have Smith & Wession stamped along the Left side of the barrel, a S&W logo on the right side and caliber on right of barrel. See picture links below
Link to a picture of the S&W Safeties: http://www.armchairgunshow.com/image...Hless-Mods.jpg
Mod 4 with pearl handles Right Hand view.