Clean again. I bought a used .50 cal once that had been bore buttered to death, wouldnt print better than 10-12" at 50 yards. I am a firm believer that Bore Butter builds up a residue over time and ruins a barrels accuracy little by little. Since your barrel is S.S., and has only been buttered several times you shouldnt have much trouble gettin rid of any residue that has accumulated thus far. The best way Ive found is to clean it real good with the hottest soapy water (or other favorite cleaner of your choice) that you can stand, (use a copper bore brush if residue is really bad) lube it up real good and let it stand for a day or two, then run some dry patches down the bore and see what comes out. If its a yellowish crud then you still got Bore Butter in there....clean it again, lube it up, let it set a day or two, run patches down to check for crud. Just keep at it until you stop gettin that yellow crud on your last patches. This little program worked for me and turned a 10-12" 50 yard gun into a 2" 100 yard gun. I took about a month but mine was really fouled up with Bore Butter bad. Hope this helps you, good luck.