I bought one of the original issue 686s when they first came out.
As soon as I shot full-power Federal .357, the primer flowed back into the firing pin bushing and locked the gun.
S&W replaced the firing pin (on the hammer) and the bushing (in the frame), which are the same parts used in later production. No problems since. They also stamped an "M" into the frame visible when the yoke is open.
The recall only affected the "no dash" and certain -1 models that had problems with primer flow locking the gun.