At 7yds, that thing should make one ragged hole in the paper with all rounds. Short barrels are the hardest to master because of the short sight radius. The closer the sights are to each other, the more amplified any imperfections become.
As long as your sights are not loose, then there is no reason that gun should not put all rounds in the same general spot at 7yds. A 686 is a superb firearm, It is my revolver of choice. You can keep your Rugers and Colts, give me a 686 any day and I will gladly step to the line with you and see whats what.