Now ? Hornady Cleaner/Lube 1-Shot (
BLACK spray can -- not the case-sizing stuff)
I used BreakFree for almost 40 years, then began looking for a spray to clean out gas shotguns w/o taking them apart beyond pulling the forearm
Lo & behold I remembered
THIS STUDY ...and the Hornady spray really simply melted/dissolved/washed off all the carbon from gas tubes, pistons, under springs, inside bolt assemblies -- and
DRIED to a slippery film within a minute or two.
Then I did a simple spray test on a cleaned/sanded piece of steel plating and left it out on my porch more than a year ago -- nothing, still shiny, not a speck of rust -- while the control plating is now totally brown and pitted.
I still use KG-1 to get carbon down to the bare metal. But Hornady gets 90% of it out in a single patch, and the 2nd wet patch gets to 99%, and I just leave it from that point