Mine's the 7.5", and it hits good. I'd say the gun's potential is half of what you are getting at twice that distance. I can't help you out with any recommendations for factory loads but I see a couple possibilities not yet mentioned.
You didn't say if you were using a scope of not. It sure sounds like some kind of a scope problem. If you are using a scope try taking it off and verify your groups at a closer distance. Check the mount screws, they don't seem to stay torqued down very well on mine. What about the internals? If you're not using a scope, try one, it'll tell you if it's the gun or not in a hurry.
How's the crown look? Lord knows I don't look down my muzzle very often. That's just sick and wrong!
I was under the impression that there is supposed to be some rotational freeplay in the cylinder and that a small amount is good for accuracy. Mine has very little, but it is there. It feels exactly the same to me whether the hammer is cocked or not.
There is one thing I've done to my gun that improved my accuracy. The SR trigger has a large overtravel. I wrapped the trigger guard behind the trigger with tarred cloth electrical tape. Built it up to act as an overtravel stop. Once the sticky wore off and the trigger seated into the tape properly it turned out to be real sweet. I can shoot double action about as well as single action now. The tape supports my finger near hammer drop allowing very fine control over the final squeeze while keeping the sights aligned. Overtravel is basically non-existant.
Good luck with your problem.
