If you take apart the sight elevation indicator plate and pull out the sight bridge arm from the receiver mount block, you should find a mark stamped on the backside of the arm. That will tell you what brand of rifle it was made for. I ended up with about 25 of those once i bought out the estate of a retired gunsmith and only a few were actually tagged from what they came off. The rest were found out the hard way.
It will be something simple like an "O" or "M" Somewhere there is a chart online that will decode it for you.
That is a very clean looking sight and should fetch a tad more then $1 online, if you decide to sell it. If i recall from my searching, the later model sights had the flat top dial while the older ones were domed. When i say late model it could be somewhere in the 50's or 60's
Nice find!!!