flitz sportsmens today with my barrel. they looked at it and said it was plastic from the sabots.
I would really have a hard time believing your "pitting" might be "plastic fouling" from sabots... Plastic fouling from todays modern sabots and shallow riflelings just does not occur that much. JB's will normally get any plastic fouling there might be. If it is really "plastic fouling" you can get to loosen by pouring boiling water down the barrel and through the nipple. The fouling will pull away from the barrel and clean out with a swab and brush.
I am afraid that what you might be seeing is "pitting."
Then back to the original question shooting a barrel with pitting.... I have a Renegade barrel that I got of the internet that is really pitted - but the darn thing shoots great. I really can see even a loss of velocity across a chrono. The thought of the pitted barrel drives me nuts, and to keep the pitting from continuing it takes more time to clean the barrel.
This is a target I shot from this pitted barrel several weeks ago. It shoots great but I still do not like the pitting...
http://img.photobucket.com/albums/v130/sabotloader/Renegade1.jpg