If the barrel is truly that bad, and it sounds like it is, I'd go to the Sinclair website and get a set of Tubb's lapping bullets. fire a course of these bullets and you will have done all you can do to help a rough barrel.
I have a 22lr finishing off handgun that would foul something awful. I got one of those lapping kits, with different abrasives, I must admit that I did a very crude job of it, but the barrel is now a thing of true beauty with little fouling troubles. After doing the paste lapping thing, I would deffinately go with the bullets with the lapping compound already on the bullets.
