what worked well for me
I know this is an older thread but I recently had to remove several layers of copper fouling in a couple of rifles and tried several products after recomendations on this site.
I originally used Hoppes Benchrest copper solvent. It did o.k. for mild fouling if I left the bore wet overnight. But it seemed to build up faster than I could take it out in my .223, which seems to foul pretty quickly.
I tried CR-10 from Barnes, wow, this stuff will clear your sinuses and your copper fouling really well. I always thought soak time was needed for proper disolve time, but you can only use this product for 15 minutes before you must attend to it. I wore some rubber gloves with this as it is a very strong ammonia based solvent. It worked very well.
Butches Bore Shine. It worked almost exactly as the CR-10, without the time limitations according to the directions. Anything that comes in a glass bottle and then packaged in a plastic container for fumes must be good is what the guy at the sportsmans warehouse told me, he was right. I put the gloves on again for this one. This product worked as well as CR-10 with a few less limitations (time).
Wipe out foaming. This is something I will certainly buy again, it worked great, without dealing without the awful fumes too. Very minimal work on my end, just let the foam do the work. At first the can seemed over presurized and I got foam all over the place. But after I got a good seal around the nozzle and got a feel for the "trigger", all was well. Great product I will definately be using this again.
Bore Tech Elemininator by gunslick. I bought this at the same time as the wipeout because I wasnted to go home with at least one that would work. This product, IIRC, was not ammonia based and not toxic and I had doubts. This worked as good as the wipe out. Same amounnt of effort to work with too. It was a more cost effective purchase, bigger can for not much more than the wipe out. Worked great. I will be using this again too.
Last but absolutely not least, Sweets 7.62. It was similar to the CR-10, and was very effective on the copper fouling. It was also limited by working time, but like CR-10, does exactly what its supposed to in that time frame. If I get some tough to remove fouling that the foams wont get the first time, this will be my go to black skull and crossbones bottle. I wore the gloves with this one too, as it seemed pretty toxic like the other ammonia based solvents.
Maybee this will help someone who was in my situation who is looking for a copper solvent and thinking of trying a new product. Everybody has their favorite method and product, and this is what worked on my rifles. All in all, I would say that all the products except the Hoppes Benchrest (because it takes soo long IMO), are good recommendations. I think the foam products are what I will continue with as they dont require a lot of work to use, no fumes, I can soak the bore overnight, and no spills to worry about.