I've never heard of that kit so no experience. I suspect it would work and cold bluing often times works better in the gel form than the liquid but it depends on the finish and the metal and all kinds of stuff, so it's like stain, you never know what your gonna get.
In Memory of Paul "Dietrich" Stines.
Dad: Say something nice to your cousin Shirley
Dietrich: For a fat girl you sure don't sweat much.
Cue sound of Head slap.
RIP Muggsy & TMan
"If you are a warrior legally authorized to carry a weapon and you step outside without that weapon, then you become a sheep, pretending that JOCKO will not come today."