My daily chore was to clean at least two shotguns every night, and if the FASTEX barrel treatment could lighten the chore, I'd try it.
Completely degrease the inside of the bore with something like Gun Scrubber: warm the barrel to 122 degrees Fahrenheit; spray FASTEX barrel treatment into the bore or run FASTEX saturated patches up and down, followed by a dry patch; and voila, you're in business.
After warming them, I sprayed FASTEX barrel treatment thoroughly down both barrels and ran two clean cotton patches down them.
In short, FASTEX does reduce the deposition of plastic, powder and lead foaling.
I might add that I also treated a heavily pitted 8mm military rifle bore with FASTEX.