Maybe I am an oddball for my age group (27yrs old) but I also use Hoppe's #9 on my AK and AR and think it works really well on the chrome lined barrels of both weapons. I also use it on my ruger MK II pistol, and my Sig pistols. Sometimes, however, I have to use something a little stronger for hard copper fouling in my Sigs (ammonia based stuff) as the Sig barrels are not chrome lined and after a lot of shooting, especially with cheap ammo, I sometimes have really stubborn copper fouling that would take too long to work out with Hoppe's #9 alone. The Hoppe's cant be beat on chrome lined bores though. I push a couple of wet patches through and let it sit while I clean the other parts of the rifle, then go back to the bore with a brush and a couple wet patches and the gunk in the bore just pushes out blue as can be on the patch. Then, just because I am anal, I dry the bore and push through a couple of patches really soaked in Breakfree CLP, let sit a few minutes, then dry completely out. Never had a problem. So, in my young and limited experience, Hoppe's is really good stuff on chrome lined bores and see no way that it might hurt anything, it never has with mine, even after extended (overnight) soakings. Hoppe's is the only solvent I will soak overnight with.