Remove the stocks and read the serial number stamped in larger size on the butt or use a magnifying glass on the number under the yoke. I’d bet a nickel there are three letters and four numbers.

All the three letter prefixes starting with AY in the SCSW are from 1987 and 1988.

Edit to add: The difference between 1987 and 1988 might mean whether or not it is new enough to have a lifetime warranty. After the gun businesses slow down I’d call S&W and ask when it was manufactured just to know if it has the lifetime warranty. I’ve been told there’s a long wait on the phone now.

Oh, and Welcome to the forum. A 6” 686 makes a great target revolver. At local action type matches the most competitive revolver seems to be a 6” 686 with an action job and cylinder milled to accept full moon clips. They’re not quite as quick to reload as 625s but they have an easier to use DA due to their shorter trigger reach.