I had a contract with S&W to do the recall work. The problem involved Federal primers cratering , flowing metal into the hole in the hammer nose bushing, and locking up the cylinder. Fix was a new hammer nose bushing with smaller diameter hole, a hammer nose with slightly shorter pin with smaller diameter. After the fix, I had to test each revolver with Federal .357 mag ammo provided by S&W. I must have gotten several thousand rounds of the ammo along with the tools and parts to do the recall work. If I remember correctly, I did approx. 700 "L" frame revolvers.
I did a revolver for our local Sheriff's Dept., and could not get the gun to work or come into specs. (we had a few gauges to be used during the work), and I had to send it back to S&W. A couple of weeks later I got the gun back with a note stating that they had to replace the frame due to poor tolerances on the original one. Out of all the guns I did, that was the only one I could not fix myself.