I have used CRC Brakleen [green tin is best] for years. It is one of the best degreasers out there. However, it does attack certain plastic finishes and will cause some clear plastics to go opaque. I do not use in on rifle parts that are in wood or plastic stocks...metal only. The caution regarding getting it on your skin is valid. Also remember to use it where ventilation is excellent, you should avoid breathing the vapors. After treating any iron/iron alloy parts they will be vulnerable to rust, since it takes all oils completely off the metal.
FWIW, it is one of the best wasp killers I have ever seen, instant death on contact. Regards, Eagleye.