I would lean more towards products that were designed from the ground up to be used on firearms. Also, flitz would leave a wax which would have to be removed afterward. There are plenty of products out there to choose from.
I think there are a couple different kinds of flitz. I used the jewelry polish flitz on a barrel around 18 years ago. I never could get it to shoot as good after that. Someone on here uses another version of the flitz and likes it.
J-B should place a disclaimer or differentiate between the two better. Many don't realize there is a difference between the bore bright and the bore cleaning compound.Yeah I ruined a bore with Flitz once. It polished instead of lapped..
A friend ruined one of his with the 'bore bright' J-B 'polish'.
J-B should not ever have made or offered that.