I have a .50 cal remington muzzleloader that has developed at least some interior rust/corrosion inside the bore. I don't always hunt with it in the late season (sometimes just bowhunt that season). The propellant has been pyrodex pellets. Rifle had been used and cleaned faithfully for 6 years. I guess I must have missed some residue and combined with taking a year off with that gun we have some rust. I cleaned again after finding it in this condition, but can't seem to get it back looking the way it should... Hot soapy water and remington muzzleloading solvent was what I used. Is there anything I can do to work some of that rust out?