I did a little test with a copper penny. I put a dab of JB Bore Compound on a q-tip and rubbed it on a penny. It shined the penny.
I did the same test with Sweets 7.62, it worked much faster at shining the penny.
I did the test again with GunSlick Foaming Bore cleaner (non-foul smelling, no ammonia, can leave in barrel for extended time) and behold: This stuff worked the best and shined the penny MUCH faster than the powerful Sweets 7.62. It remains my favorite copper remover.
I had a heavy copper fouled 1918 dated barrel on my Model 1917. I was shooting the bore foam down the barrel for several applications over a period of days and letting it drip out, and it continued to come out dark blue indicating copper. I was getting frustrated not being able to get the copper out so I opted to try the Sweets 7.62 and JB Bore compound. Perhaps the initial cleanings with the bore foam removed most of the copper, as I followed the directions with the sweets and the JB and applied both of these cleaners 1 times, followed by another application of the GunSlick. This time, the gunslick did not turn blue indicating copper.
It makes me suspect that although the foam seems to clean the copper the best, either the Sweets or the JB compound finished whatever remaining copper was in the barrel to which I can not understand if there was only a small amount of copper left, why the gunslick did not lighten up in color prior to the applications of the Sweets and JB.
Perhaps a layer of power fouling caked onto a layer of copper (as I understand, copper and be layered between power fouling) to which the Sweets or JB loosened up. The gunslick does a WONDERFUL job of removing copper but doesn't seem to do too well a job at removing power fouling. I tend to use Hoppes and such for this. The first patch with the Sweets pulled a lot of black crap out of the bore.
This is a mystery.
I did the copper penny test with Kroil Oil and it did not shine the penny.