Dave: I agree with the 54 1:72 twist for round ball. I have two different 1:72 twist guns and they are hard to beat when it comes to accuracy.Check with Doc , awhile back he had a Bridget Hawken 58 cal with a 1:72 Kelly barrel in a 1:72 twist . It was for sale either unfinished or finished. I myself prefer the 54 also over the 58.