What is the value of smith and Wesson 657 mountain gun?

There are several variations of the 657 mountain gun. these are indicated by a dash (-) and a number after the model #. The general rule is the lower the number after the dash the earlier the manufacturing date and the more valuable the gun. unfortunately it is not that easy. There many other factors that determine value and each gun needs to be appraised individually. To be very general, Model 657's values range from $500 to $1000. Mountain guns usually bring a premium.