I just went through this two days ago...

I bought a used 4" 624 on Wednesday evening, but could not finalize it until Thursday morning since my "instant" background check was not so instant. On Wednesday evening, I was searching for info. on the 624 on the net and discovered the recall issue. I called the shop first thing on Thursday morning and got the serial number (AHBXXXX). I then called S&W and they said the gun WAS in the recall period. The issue is that a steel supplier sent S&W the wrong type of stainless for the cylinders and any 624 made from 01 JAN to 08 JUN 1985 could have a problem. Without digging deeper, S&W said they could not tell me if my specific gun had been checked by magnafluxing, but all guns that were checked and OK had a "F" stamped on the back cylinder face between two of the chambers. I called my shop back found out that my gun had a "F", so I am good to go. When I picked-up the gun, I took the grips off, and grips were dated 17 FEB 1985 .

Hunter