The CS1 is a far better revolver than any stock 686 made - pre or post lock.
There were demanding requirements for durability and accuracy that had to be met by S&W to satisy the customs service contract. Periodically CS1 686 revolvers were taken from production lots and tested for many thousands of rounds.
SmithNut told us of these requirements some time back in a CS1 thread. I can't find the post, and have not seen SmithNut here in some time.
IMO the only thing a CS1 and a current production 686 have in common is that they are both chambered for .357. Regards 18DAI.
You are right. I own 2 three inch CS-1's now. And owned 2 four inch CS-1's before.
They seem to shoot better than other 686's.