Perma Blue Paste by Birchwood Casey

Rust is never your friend, especially with firearms...  If you have a old blued rifle or pistol that is scratched, or maybe had some machining work done to a firearm and now have exposed metal, bluing will save you from rust.  The easiest bluing I have found, is the Perma Blue Paste Gun Blue by Birchwood Casey.  It has a great gel consistency which makes it easy to work with.  And by using repeated coats, you can get a darker and richer blue if you want.

You can find the Perma Blue here: https://tinyurl.com/359yw6kv