I've recently bought a Ruger old army. Everywhere I read says to use a .457 ball and work from there with different powder loads to find the most accurate load. Allegedly the .457 should be shaving off a ring, but it doesn't with my gun. At best i can shave off a sliver from one side of the ball. No matter what powder charge I use I can't get better that a 3" group at 15-20 yards. Been using graf and sons FFF powder. I'm wondering if maybe they made a larger caliber version that I don't know of or maybe this is just normal for the ROA?