The German Army adopted Ballistol in 1905 as safe for wood, leather, and metal. According to USMC friends they are still using it in Afaghanstan, indeed they use it as a cooking oil. It works very well on copper/lead if sprayed on while barrel is still warm from shooting-like at the range before returning home. Smells a tad "funky" but it does work and is very economical. I believe it is mineral oil based. It is also used in Europe the way we use "Udder Balm" skin cream. Best, Dr. Bill