Neither K-1 Kerosene nor Ed's Red Bore Cleaner will damage factory bluing ...
The model 58 in my avatar had a lot of light surface rust and freckles ... a motorcycle cop in Louisiana carried it , lots of heat , humidity and rain ... but the light surface rust cleaned up nicely with the following method ...
I used a soaking in K-1 Kerosene to start ... a week .
Then followed up with a cleaning / polishing with Turtle Wax Chrome Polish and Rust Remover ... apply TWCP&RR to a soft cloth and rub / clean & polish the surface ... the red rust will be removed , any and all factory bluing will be left intact .
Don't use any machines ... hand clean with a folded cloth , work on small areas at a time .
This is the safest method I know to remove light surface rust ... most commerical rust removing soaking agents will remove the factory blue ... Be Careful with them !
I've tried the copper penny thing ... but didn't get good results ... K-1 Kerosene and TWCP&RR works best when trying to save a blue finish and remove light surface rust ...
that's what saved my model 58's original finish .
To remove rust from a firearm ... you will need to do a little rubbing ... you can't just soak it off .
Better than a copper penny ... Copper Wool ... it's like steel wool but made of soft copper ... Brownell's sells it , safer to use than steel wool .
Good Luck ,
Gary