That would appear to be a dash 3 inspcalahan. You could confirm it by calling S&W customer service, giving them your serial number and confiming it is a 4506-1 revision 4.

You and mbliss57 have early production revision 4 dash 3's as evidenced by the forged hammers. Only the first few batches or 4506-1 (R4) "dash 3" had forged hammers. There are also some that the owners changed out the MIM hammer on for a forged part. The vast majority of production of the 4506-1 R4 dash 3's having the black MIM hammers and triggers.

My early 4506-1 R4 dash 3 is a VAV prefix and has the forged hammer. My later production LAPD 4506-1 R4 dash 3, with factory adjustable night sights, is in the VJP serial prefix. It has a MIM hammer and trigger. Hope this info helps! Regards 18DAI