I would give the good folks at Lobo Gun Leather a call. While they do not specifically show the 686 SSR on their handguns accommodated list, I have ordered holsters for guns not on the list before without problems, but I did contact them asking if it could be done. They also state in the list under S&W revolvers "Most revolver barrel lengths and configurations accommodated". I am sure they can and will set you up nicely.
Lobo Gun Leather
A good source, in my opinion. During my many years in the business it was always my experience that most of the big name holster makers concentrated their production capacities on the most popular and common handgun models, with others largely ignored as uncommon and unprofitable for production efforts.
The SSR series is one example of a rather unusual and relatively small production piece for which holsters are not commonly available. Choices are limited to either a "make do" approach (choosing something fairly close that will accept the piece) or a custom maker (frequently requiring the owner to make the handgun available for patterning and fitting the holster, a risky and expensive approach).
Our approach at Lobo Gun Leather has been to offer holsters closely fitted to the common aspects of the revolver (frame, trigger guard, sights, etc) and barrel channels that will accept the more unusual aspects such as barrel profiles, lengths, underlugs, rails, etc. This has proven successful with several holster styles (Model 5, Combat Classic, Threepersons, and some of the pancake designs).
As long as Mark Fedders and his crew (current owners of Lobo Gun Leather) understand what is required and what the customer is trying to achieve there should be no problem. Very talented people, and very good to deal with.
Best regards.