Bisphenol A in Hard Rubber?

I want to buy a product partly made of "hard rubber," the product description says. But the wikipedia article on natural rubber says that to vulcanize it sulphur, peroxide, or bisphenol is often added to make it tougher. How can I find out if biphenol A or one of the other three is in this product? The product in question is a revolver and the "hard rubber" part is the grip. Thanks for any help.