I've tried KG-12 and didn't like it at all. I used it as directed and gave it plenty of time to work each time. There was no color on any patches, so I couldn't tell if it worked or not except that copper streaks near the muzzle were still present. The real test, though, was when I followed the KG-12 with traditional ammonia based solvents. There was a considerable amount of blue coloration on the patches indicating appreciable amounts of copper remained in the bore after using the KG-12.
You don't hear much about these KG products and I think it's for a reason.