drotis: In addition to the above responses, I have learned of some tell tale things to look for from previous posts on this forum. To summarize, the first thing I look at is the sideplate fit. On original guns, the line is very fine. On refinished guns, the sideplate is many times polished so that the sideplate edge is rounded some and it makes for a larger seam. Once you make a couple observations of refinished guns, you will pick this up pretty fast. Another tell I look at is a soft looking cylinder, flute edges more rounded and the stop notches and approaches will be more rounded. Also, check the front of the extractor rod, it should be in the white as it is fitted after bluing at the factory. Also, with gun in hand, check for pitting under the blue. Sometimes, polishing is not able to remove all the pitting and this is visible, when moving the gun around under the light.
There are some refinishers that can refinish a gun that is difficult to determing. The factory was very good at refinishing that was as good as original. Today, the color is different from the old finishes, so that can also be visible.
On prewar guns, the pins on the left side above the grip are usually rounded from the factory and are polished flat on a refinish. The pin above the grip on later ones that were issued with Magna grips that covered the pin may be flat from the factory though.
Look at a lot of guns with a critical eye, and you will soon be able to spot the obvious ones.
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