Thank you very much! You’re a gentleman and a scholar good sir.it's surely a model 15 and is wearing diamond Magna grips from before 1968 and I believe the serial number also places it early to mid 60s.('63-'67)If you open the cylinder the model number should be stamped on the frame just above the pivot point. It's a wonderful firearm. Looks like it has seen some use. In todays market it is worth in the $450-550 range..just going by pictures.