Hoppe's will, very gradually, attack copper, so you are correct that the green you saw was that, but it's a piker compared to what Eliminator does. Run a patch in and let it sit just two minutes and push it out and it will be an very dark cobalt blue.
And there are still others that have appeared since the article was written or, at least, were not well known then. KG-12 is probably the best copper remover. It will take off more with one patch worth than any other. But it does not turn blue or green. It just gets a darker orange brown, so you need either a bore scope or Eliminator or some other color indicator to prove the copper is gone. KG-1 Carbon remover is also good. But Eliminator is still the best all-purpose cleaner, IME.
The Slip2000 works well and their synthetic gun oil is good for not burning down to become more carbon in the bore.
My favorite trick is to carry a small pump sprayer of Eliminator to the range, and as soon as I'm done and before the carbon has time to harden, I pump a couple of squirts into the chamber and let it run down to the muzzle. I then plug the muzzle and chamber and head home. When I get there, most everything patches out with just a few wet patch cycles with time to wait inbetween (usually just 5 minutes, but you can leave it much longer if you have other things to do; 20 minutes like in the article is fine, requires the fewest total patches, but is not as quick as several 5 minutes soaks if you are in a hurry to put the gun away).
