I use a silicone spray made for the meat cutting industry. It dries to a light haze and has never failed me yet. I believethat an ounce of prevention is worth more than a pound of cure so I field clean myBlack Diamond after every half-dozen or so shots at the range. Using Pyrodex pellets (150 gr), I don't have as muchbarrel fouling as usual. I also season my barrels using bore butter. This helps to make cleaning a lot easier.