Check out these two targets. Both shot from the bench at 50 yards with the same load/patch thickness/lube. One with a .562 ball and one with a .575 ball - only .013 larger in diameter. Clearly, the smaller ball needs a much thicker patch.

I'd try that smaller ball with 2 .018 patches...That might still not be enough as there is .013 difference in the diameter of the 2 loads...

Semi, Did it take any pressure at all to load with that smaller ball?

Well Captain Obvious it appears once again you are correct in your assumption. And if it were me, I wouldn't screw around with those smaller balls and as much as you like to cast, I would remelt them and cast more .575" balls. That is unless you have a rifle that shoots the .562" balls. That second target is really some good shooting and looks like you have found that rifle's combo.
You must be getting tired in your old age. Your reports are getting very short. Ahh its probably the heat down there getting to you. Its OK, sit on your rocker in the AC and sip on some lemonade or sweet tea and relax.

I could thumb start it flounder, which was kind of what I was looking for. But, of course, I was hoping for a little better accuracy than that.

"Captain Obvious" bronko, "Captain Obvious"? Surely you jest. My secret identity is Major Mistake.

As for the short report, it has nothing to do with my old age. I have come to realize that some of the seniors on this forum have a limited attention span, diminished comprehension ability, and eroded reading skills. I tried to make it short enough for a decrepit old fellow like you to understand.

In that case, I apoligize to you sir. I am usually correct 97% of the time. So who cares about the other 4%.

When I shot the .575 ball you sent me, VS the .570 in the Green Mountain barrel I really did not notice all that big of a change in accuracy, but it is just my opinion, that going to the smaller ball would cause accuracy to suffer. Unless you went with perhaps a blue jean pants patch. Something really thick.

Also I was able to read all of that post in one day. It was short enough.

Cayugad, I haven't seen any difference between the .575 cast Lee balls and the .570 Hornady or Speer swagged balls either. And the .570's are a tad easier loading. But dang it, Lee does not make a .570 mold.

When shooting long range and bench competition with PRB I have noticed that the people that do not use a tighter than normal patch and ball usually a ball 5 thousands bigger that the norm for the caliber are the first to fall by the wayside. I believe that the tighter combination controls slippage so that the ball remains stable at longer range.