Double Amen to the cylinder wall thickness. It's usually not the frame that goes, but the cylinder. Using +P loads might be done but most ammo companies don't recommend it. IF you have any doubts what so ever, call and they will give as good of an answer that they can.
One of the reasons Ruger's shoot heavier loads is both the cylinder wall thickness and the top strap not the action or method of construction. Ruger had the advantage of starting with a blank sheet of paper.