This is always an interesting subject because those who MUST wipe frequently, seem to feel that in all the world only they must wipe in order to load the next shot. Let me assure everyone that such is not the case.
I own both radius groove and square groove barrels and they behave exactly the same loading and shooting; round bottom does clean up a little easier, however. I use either Goex or Jacks Battle Powder. I usually shoot three to four dozen shots at each range session and rarely need to wipe before I pack up to go home. I much prefer spending my time loading and shooting than wiping. The chronograph shows that (not wiping) has no affect on velocities and the targets show that accuracy does not deteriorate. I've found that Hoppes #9 Plus BP lube, spit patch and Black Solve all three allow continuous shooting without wiping. My favorite is Hoppes as both Black Solve and spit patch dry out quickly and I dry out even sooner. Basically three things must be addressed in order to shoot (accurately with uniform velocities) dozens of times without wiping. These are:
1. Use one of the above mentioned lubes - there
are probably others but my experience is
only with these three.
2. Use enough lube; damp is not enough, WET is.
3 The ball/patch fit must be tight. Tight
meaning that the prb should go down with
enough protest that the rod has to be
gripped only a few inches above the muzzle
and seated in short pushes; no one or two
pushes to seat type grips. If you are
afraid to do this with your (quality) wood
underbarrel rod, then it's too tight.
That's it in a nutshell; no magic or special technique, bore, rifling, caliber, etc, etc.
About the patches; thicker is usually better. And they should be WET; not drippy but definitely WET. DAMP patches won't work. I like to put an op wad between powder and patched ball but it isn't at all necessary just to protect the powder. I load .311", .350", .390", .440" or .445", .490" and .530" balls in the respective calibers; but ALL are patched with a .024" (my measurement) ticking. Thinner such as .015" to .018" can work okay but thicker is better.
If you like to grab the rod half way or near the top to seat; DON'T; you'll break your wood rod and skewer your palm at the snug fit levels we're discussing.