Most of my animals are killed with a taped barrel. As soon as the animal is down, I'm putting new tape on. It's not so much the rain, but the fact that I don't want debris in my barrel and to protect my crown.
I learned to do that the hard way 3 years ago, shot, did not tape again, rain, blood, rusted crown...then cut off two inches to 22!
I prefer brown or green electrical tape depending...now if I had one of those high gloss Aborts I would not worry about taping as the trigger group would rust tight well before any barrel problems would occur..