Smith & Wesson 686-4 Model Meaning | Firearm Specs

Question
Hi,Im from australia, I have a smith&wesson 357 mag 6 shot, it is a model 686-4. What I would like to no is the-4 on the end of the 686.I no what a model 686 is but what does the 686-4 mean?I can not find this ifo on the internet.
Thank you.  

Answer
Hi Brad,

What you are referring to is the "dash number". S&W uses the dash number to designate a variation of the model number. IE. 686-4 , 686-5, etc. each dash number indicates a change in production specs.

In your case (686-4) the "-4" denotes a change in the rear sight and extractor.

Thank you for your question.

Sid Lark