Are you sure about the Kroil?
I have used brake cleaner on semi auto frames for cleaning, and Kroil on bores as well as stuck rusted bolts on machines. They seem to be very different.
Kroil is absolutely the best. It will "float" any fouling out of the barrel.
The brake cleaner is good for powder fouling, and bullet gunk and plastic residue (shotguns). Think about about -what is brake residue and fired powder?
I use the Kroil if I have it, and brake cleaner when I don't. IMO they do the same thing by different methods, and are reasonably cheap. I guess my post is you don't need some $8 a bottle fairy dust to clean a gun.