Do not use 70% isopropyl alcohol, that 30% is a mineral oil. It's rubbing alcohol that is designed not to dry out skin. If you're going to use isopropyl, you need to find the ultra purity stuff that doesn't actually leave a residue.
I vote for the dry patch with single piece nylon rod. If I have my hopup rubber off for whatever reason, I then clean with some Hopps #9; really polishes the inside. I think it's probably overkill, but I had some lesser quality chinese barrels that had some crappy tarnish inhibiting grease in them... didn't affect the accuracy of cheap BB's (it sucked), but was a dramatic improvement in consistency with good BB's after I cleaned it (Go Green Devils!)
Basically I only use Prommy barrels now, dry patch keeps them beautiful