question is, where do you get feed grade molasses if you aren't in a area of the country that would have feed stores for agriculture.
Next what quantity do I have to buy. What kind of price?
Depending on the rust how hard and tough etc.
Plain mustard or vinegar will work also.
As will lime away or it's generic equivalent.
But again, caution must be used both for the gun and the human body.
All three will remove the bluing also and perhaps the color case hardened coloring if left too long.
If the rust is very heavy and stubborn add a teaspoon or so of salt to the solution.
Completely submerge every thing. let soak, swish a bit. any where's from an hour to a day or so, just keep an eye on it.
use a 3m pad or steel wool to wipe away. Repeat if necessary.
now fill the container with water, add a couple tablespoons of baking powder. dissolve well then soak.
this neutralizes the acid. remove wipe clean.
wipe down with denatured alcohol then do whatever you were going to do. blue, brown, polish. lube.