Picked up my friends 629 stainless 44 mag. Beatiful shooter but my friend (love 'em like a brother) never did a proper cleaning on his guns. I have some moderate copper residue on the front of the wheel. I have liberally applied the hopps copper solvent rubbed and briushed (nylon) and nothing! I smeared it on anmd let it sit for 10-15 minutes and rubbed and brushed again...nothing. Any suggestions on how to get this stuff off???