soak in oil ,bore brush it , re soak , re brush , re soak, inpect , shoot some ,repeat and you might see improvement ,but damage is probobaly done ,take better care of guns or whoever had before u , it might clean up, use good judgement if it is really bad . my uncle found a 1100 20gauge rem in the woods some drunk hunter probobaly lost all pitted and rusty and wet and dirty he cleaned and in fired perfecty it is ugly as u know what