Just out of curiosity how thick is your blue jean material. JMHO but I have found that a larger ball and thinner material make for a better group. If you are using old cut up blue jeans you might find that the thickness of the material varies depending on wear. worn blue jeans are full of abrasives( from the laundry soap and what ever else they have come into contact with) and the same material used to slick up your bore may wear your bore out prematurely.