686 (1980): No dash, Begin regular production.
686-1 (1986): Radius stud package; floating hand.
686-M (1987): Recall by S&W and overstamped to indicate a modification by the factory or warranty station; applies to 686 and 686-1 only.
686-2 (1987): Change hammer nose, bushing and associated parts.
686-3 (1988): New yoke retention system.
1990: 2-1/2" barrel introduced.
686-4 (1993): Change rear sight leaf, drill and tap frame, change extractor, introduce Hogue grips.
1995: Introduce power port barrel.
1995: Introduce 7-shot cylinder with seven flutes in 6" barrel length with round butt frame. Serrated backstrap, smooth trigger, 7-point star extractor, RR front sight, service hammer WO rear sight blade, Hogue grips with S&W logo.
1996: Delete square butt; begin shipments in a foam-filled blue plastic case.
1997: Change thumbpiece; ship with Master trigger lock.
686-5 (1997): Change frame design to eliminate cylinder stop stud; eliminate serrated tangs; change to MIM hammer with floating firing pin, change to MIM trigger, change internal lockwork.
686-6 (2001): Internal hammer and trigger key lock.
686-7 (2002): Performance Center variation in .38 Super.
Dan