Great firearm...do a search on this or some of the other forums you'll find a wealth of info...started out as what is referred to as the "pre model 39" which meant the Model 39 was not marked on the gun..then SW started marking the pistol Model 39..then after some minor design changes, the Model 39-2 came to be..all in all, production ran from early 1950s until early 80s when the model was discontinued. In some folk's view, one of the better fitting pistols made. Again, do some searching and you'll find most of what you want to know about this model.