I have some of the jb bore paste. I had to order a can of kroil online. Could not find any locally. Years ago I used an ammonia based product on a badly fouled bore. It did clean up the bore but after that it seemed like it got dirty a lot quicker than before. This was while using cast bullets. I think the ammonia might have etched the bore and it would lead up rapidly. I will give Capt. Frank's method a try. There is no telling how this rifle was treated before I acquired it. It does shoot nice. I want to start shooting cast bullets in it so I do not want to use any ammonia based product.