Experience and handling many, many examples are the only true school for evaluating a firearm.
That being said, I look for sharp, well defined edges on all surfaces. Well fitting grips with no overlap, no shortness and no slop. As you mention, crisp and well defined markings. Proper overall wear and finish colors.
Short of visiting an extensive collection with someone who has profound knowledge of the subject, I would purchase as many books as you can afford.
|