I inherited a Ruger Mk I pistol recently. It is the standard model with the fixed sights and a 5 inch tapered barrel. It shoots OK, but not near as well as my High Standard Citation heavy barrel. I would like to at least change the sights on it. A heavier barrel would be nice, too. I have competed against guys with Mk III heavy barrels and those guns seem to shoot real well. Not knowing a lot about this model, what are my options? Who are the aftermarket suppliers that may be able to help me out?