Hi Folks, Just an update. The combined wisdom here was correct and very helpful to me. Many thanks!
Over the week I did some "similar triangles" computations, and adjusted my rear sight. It was pretty close to right-on today at the range.
I backed up from 38 to 45 yards. I also changed to .020 patches (thicker), and revised to the suggested method of lubing the patches.
I obtained a screw-on lid shallow container, and placed a stack of 20 patches inside. I then dribbled Hoppes patch lube on top until they were all saturated. Not soaking. That worked like a charm. No fouling of the powder, but no issues with the patches burning.
Ram-rodding the loads today was not bad, certainly no harder than with .015 or .018, so all good. Much better than when I was about to collapse trying to ram the loads before.
Today I wiped between shots with a damp patch and then a dry one.
So.....that means .495 roundball. 020 patch with Hoppes Lube. 65 grains 2f. Rice barrel. Chambers Late Ketland. Damp patch wipe between shots, followed by dry one. Using a steel range rod. Swiss Null priming powder.
Last week the load .018 load gave me a cloverleaf at 38 yards, but the patches looked burnt in places. This week I think the gun wanted to cloverleaf, but my glasses gave me a fit fogging up in the humidity. I would say shot #3 nearby was my fault, not the gun.
The patches all look consistent. No burn-throughs.
I also did some plinking at 45 yards and hit each of the targets (tin can and a rubber ball target) offhand. I felt great about that! This may be the best offhand gun I have shot. That Southern Classic barrel contributes to great balance.
I think I am settled. I am not sure I need to change anything at this point. What do y'all say?
Many thanks again, and God Bless, Marc