If it needs cleaning, this is the stuff
http://www.slip2000.com/blog/precision-shooting-magazine/
For my background, I took up target shooting 6 years ago or so. Its recreational, never going to be good enough or afford to be good enough to do competition though I may play at it if I manage to retire.
I think I have picked up a lot that makes common sense as opposed to the Urban Legends of the shooting business.
If I have an opinion, its stated as suchy (or a feeling or its just how I like to do things because it suits me, not because I have decided that what suits me is the end to all things
For barrel break in, Shilen (one of the top aftermarket button rifle custom barrels) had the most honest answer that makes sense to me, "it makes no difference". People keep bugging us so here is the wisdom.
I have done 3 custom barrels (all stainless) , it did 't make any difference how I did it, the best shooting one (Shilen) I just shot and cleaned a couple times during 50-100 rounds of shooting.
So, shoot it 10 or 15 rounds and clean it, repeat. That barrel shoot as good the first shot as the rest. The others like a fouling shot or two.
No one has setup up a real scientific study and proved anything. So its really supposition unless someone does (not likely, they know how to make good barrels and doing a definite study would cost a lot)
As for copper, I have not run into it, I don't shoot any of the calibers that go over 2800 fps so I am not into that arena.
As for cleaning, this article was by far the best, he went about it right, used a boroscope to confirm (I have a Lyman now, his was the better Hawkeye)
http://www.slip2000.com/blog/precision-shooting-magazine/
What I found agrees fully with his findings, the Carbon Killer 2000 works better than anything on carbon. The Bore Tech Eliminator
does copper the best I have seen (and he does not say but it has a decent carbon component as well). I do get older guns with some copper in them so I have tested it.
Both are non haz, non toxic (my wife was having issues with Hoppes in the shop leaking into the house). They use focused chemistry rather than brute force dissolving to do the job from my view.
Without a boroscope, the bore may look shiny, but the boro scope tells you what is down in the groves and you can see the CK2k or BTE working.
I have developed my own variation on how I got about it, partly as I hate to clean at home as I need to get to the range ealry to get a bench and I run late and don't get them cleaned, so I clean after I shoot X rounds (usually 25-50)
This is for the CK2K as I don't have copper. I shoot when the barrel is warm, that helps the process and about 3 cycles and the barrel is clean. If I can time it I run the CK2K through and soak the barrel as a cease fire is called, then it soaks while people go down range and I resume cleaning when the line is hot again.
I use a nylon brush, I have an eye dropper bottle, I drizzle the CK2K on the nylon brush which holds it pretty good, run it through the barrel, drizzle it again on the other end, then 3 to 5 strokes, the nylon brush is out the barrel on the last one, I drizzle again, pull it out and run a dry patch through.
I repeat that about 3 times and its clean. No black and a light color stain on the last patch. I run a final patch through to get the last chemical out of the bore.
You can do the same at home, takes a bit more.
We had a family 270 (Finnbear) that the best I could get to shoot with handloads was 1.5 inches.
Once I put the gun through the regimen its shoots 7/8 at 100.
It had been cleaned after each shooting with Hoppes, it just never got it all out. With the boro scope I could see the 50 years of carbon that had never quite got cleaned out build up. That one took some time as I wet the barrel with CK2K and then let it sit. There was no copper to speak of in it and what there was came out with the BTE.
The Lyman runs $170 or so on sale, worth it if you have a lot of guns and need to see what you are doing.