The most effective thing you can do to improve your accuracy is to match the chamber diameters with the groove diameter in your revolver. The chamber diameter should be 0.001" to 0.002" larger than the groove diameter.
How I check it:
Push a pure lead ball through the barrel with a wooden dowel. Then see if the swaged down ball is bigger or smaller than the mouth of the chambers...if the swaged surface of the ball enters the chamber mouth, you are good to go. If it won't go back into the chamber (meaning the barrel is a greater diameter than the chamber mouth), accuracy will suffer.