Eldeguello ,
I' ve used nothing but Bore Butter for lubing and storage since I started muzzleloading , and I' ve never had any trouble with rust . Is it possible that your ML was simply stored in a place with high moisture ? Did you take any other precautions to avoid rust such as keeping the gun in a silicone impregnated sock ? I just took two guns out of storage for the upcoming seasons , and there wasn' t a speck of rust in either one . Both were stored in my bedroom closet in silicone socks and soft cases .

I realize that few products ever live up to the hype that may surround them , but Bore Butter is definitely one product that has performed flawlessly for me . Fouling between shots with Pyrodex RS has been minimal , I rarely have to swab between shots , and my balls and sabots always slide down easily . The opinions on " seasoning" vary considerably , but I' ve been very pleased with both the protection and ease of load that I' ve gotten with the product .