sabotloader, I have a Grey Hawk in 54cal. with the same problem,actually it is just rusted at the muzzle end of the bore. I've used JB Bore Paste,steel wool,Hoppes,ect. The rust is gone (the gun is stainless) but the small pits are,or were still there. On advice of a friend I started shooting my patched balls with JB Paste for patch lube,this helped out on the smoothness for loading the gun. Yesterday I got brave and used Valve lapping(grinding compound) on the patches. After 5 shots the gun loads like it has a new barrel. I was all set to order a new GMbarrel for it,but found that they don't make a replacement barrel for it. It's basically a T/C New Englander in stainless. But now since it shoots so well,I'm not even considering getting a new barrel. The gun drives tacks with 80grs.7772F and a patched .530 round ball. The valve grinding compound is VERY aggressive,check it after every shot. It won't take long,and it will load smooth! Ron