I purchased a 1 lb metal can of IMR 4064 from the gun show. As I went to use it today I noticed rust dust coming out. Upon looking in the can there is a light coat of rust on the inside. The date stamp on bottom of the can is 1993 and I did have to peel off the top seal. it is just going to be used as plinking rounds so I just want to know if it is safe to use.