Originally Posted by 2152hq

The scratches on the side plate are pretty serious for a cold blue to make them disappear or even improve them much at all.
The use of a cold blue especially on a flat surface like that generally ends up being more of a visual let-down than the original scratches were.

Once in a while a cold blue will 'take' on a part and you will get a beautiful blue. But most times attempts to fix a scratch ends up in the 'I guess it's better than nothng' colume'.

A bit of rust down in the scratches can be gone after with plain oil. Let it work for a while. A long time if you want to. It's not like it's going to rust the part away before your eyes.
Keep using normal cleaning procedures and most if not all will loosen and come out with that.

As far as going after it with steel wool, or bronze wool.
Take your pick, neither will remove bluing if used correctly.
Always use with oil, never use it dry, especially the steel wool., and use the finest grade steel wool 0000 grade for this.
Light pressure, don't scrub, just gently allow the oil and steel wool to do the job of removing that rust which is loosened and floats away with the oil.
I have used 0000 steel wool with oil on blued firearm surfaces for over 50yrs, 30+ as a full time restoration business and have never damaged a one firearm.
If I thought it would do damage, I certainly would not use it on any Parker, H&H, Purdey, Colt SAA, AH Fox or any other arms I've worked on.
I've never had nor used a bronze wool in that time. But it is certainly up to the job at hand.
If you feel more confident useing Bronze for this, then certainly you should use it. It will do a fine job as well.
But 0000 Steel Wool w/oil used correctly is not a blue-remover

Yes Bluing in most of it's applications is a form of Iron Oxide. But they are not all applied the same nor is the surface finish always the same.
The steel alloy and heat treat of the metal makes a difference in how it responds when applied as well.

It makes a difference when choosing how to go about saving what is still there while trying to remove red-rust that has accumulated.
There is no miracle touch-up blue no matter what the marketers tell you.