I've never used the green flitz. Sounds like it may be ok. I had a bad experience using the blue flitz in a barrel around 20 years ago.Mike, my bores were shiny as a mirror when I bought the barrels. They are still that way. They get only very minimal carbon fouling which is easily removed. Never had a carbon ring and very seldom a trace of copper from the Barnes copper bullets. Been cleaning this way for years and won’t change a thing. The 6000 non embedding grit in flitz isn’t even classified as an abrasive and does no damage. I have match barrels from shilen, hart, pacnor, Krieger, PBB and all are pristine.
I use the green liquid flitz, not the blue paste. Call and talk to flitz, I did before I used it.