I have .530 and .535 balls along with 0.10 and .18 patches. I only had time at the range for a few shots so I used .530 and .10 patches just to see if rifle worked. It felt pretty loose and my powder load was light also. I will lol into the crown I didn’t know I needed to. Going to range this weekend and will play. Now I have to build the SMR that I bought forever ago. Then build the rifle I started back in the 70s these kits are a lot easier:)