This should help. If Ruger's mother produced a lot of pups and 100% were sables the odds are petty good she was sable x sable.
Ruger did not get sable from his father clearly. so he could be sable x bicolor or sable x black.
So there would be a chance if bred to a black and tan that he would produce a black and tan, of course there could be other things...........because the black and tan dog may carry bicolor or black
Don't let the "breeding announcements" throw you. The link is to Ehret's color chart page
Ehret German Shepherds - Breeding Announcements