Tyson - from the information given, I believe there are at least three possibilities. Can you post a photo or two? If not . . . is there a safety lever that runs along the backstrap? If no safety, then is there a trigger guard. If yes, is the back of it rounded (convex) or more-or-less straight (slightly concave)?
Daniel501 - ACK prefix would date the gun to 1983, and it should be a "no dash." That's well prior to the introduction of MIM parts, which makes the gun more desirable to some. Price will vary depending on condition, but used 686s seem to run in the $500s when in good shape.