Old Remington Kleanbore Ammo

With my old H&R .32 I got a box(50 count) with 25 bullets of Remington Dupont Kleanbore .32 S&W. The lead has a heavy coating of white oxidation. Does this do great harm to the ammo, and should it be removed? Also, the box has no zip code so I am sure is was made before 1964. Any date ranges one of you can tell me that might provide a guess to the ammo's age?