That's what you have, alright. Usually contracted with long use of 125 gr. Magnum loads. I had two Security Sixes that got worse than that. They eventually started spitting to an unpleasant degree at which time I sent them off to the factory. Ruger rebarrelled both; one gratis, the other at a reasonable charge.
It's likely that S&W still has replacement barrels for 686s. About a year ago I sent in a 19-3 with similar erosion and some endshake. They were able to turn the original barrel back about two turns, remove the eroded portion of the throat, and recut the forcing cone area. Presto-change, "new" barrel breech and throat.
I still shoot 125s but much more sparingly nowadays. I'm thinking of trying 140 grain loads one of these days and reserving the 125s for TEOTWAWKI scenarios.