I have a few more to try, there are some food industry carbon removers, and there is also some stuff from Mercury Outboard in a spray can.
The food industry stuff might be a little tuff on guns.
For the record, I had a piston from a snowblower engine I used for a test bed. I put a couple well known gun potions on it, and the Tec 1005002 too.
Results were minimal with the gun potions, but the TEC part softened up the carbon to the point a brisk rub with a paper towel exposed the machined aluminum surface of the piston very nicely.
My primary use is taking the carbon out of rifle barrels, and I have found that even after you remove the copper fouling, a goodly amount of carbon can remain in the bore.
A few soak and patch sessions is an eye opener, patches and juice come out black the first couple times.
And do clean rifles shoot better? Yes, after a couple shots to lay down just a little fouling in the pores.
HM