Just goes to show you how different barrels from the same manufacturer can be. Mine loads with .530 balls and .018 pillow tick fairly easily. Last session I used denim patches that measured .021/.022, depending on how I handled the caliper. I had to give the short starter a pretty firm bump to start the load, but they loaded fine. After discoveringhow much better my Zouave shot with .575 balls and a thin patch, instead of .570s, I figured I should try a larger ball in the .54GP with some .015 and some .018 patches. I've got some Hornady .535s on the way for a trial.