[Doug]

My standard approach is to do the following.

1) Disassemble the gun and check if all parts match. Check the inside of the side plate for the first two digits of the serial number. This will be one digit higher on WWII guns.

2) If you are buying a rust blued gun I use a strong light to see what the patina looks like.

For salt blued guns smell it for cold blue (it has a different odor). Also all parts should be fairly uniform in color. Also check to see if the milling marks are well defined. Use a 10x loop to examine proofs for signs of buffing.

3) Check to see if the inside is in the white (rust blued only)

4) Check to make sure the breach block isn't cracked.

5) Lastly be objective, don't talk yourself into a compromise. If something just looks wrong research it and prove it either right or wrong. I find myself sometimes trying to find reasons to keep a gun that my gut tells me has been "worked" on.