I have for many years soaked dirty rusty receivers in a bath of the following with nothing but great results.
Prolix biodegradable gun cleaner
A bit of Hoppes #9
A bit of Liquid Wrench
And I thought I put a dash of Simple Green now and then.
I have soaked many old SXS" in this many times with no adverse effects.
My partner topped the bath off with a bit more Simple Green
the other day.
Receiver soaked for 3 days and today took it out and the nice color case hardened metal is now a dull gray in some spots.
Out of the tank it was similar to paint coming off after using stripper. Maybe a clear coat.
Any ideas what happened?
Is it possible to have a fake or painted on color case hardened con job finish.
Thanks for any ideas.
3 days? Were you cleaning a gun, or making kimchee?
It seems to me that deep cleaning on a shotgun comes down to removing one of two types of goop-old, factory or otherwise applied varnish, or old lubricant, that with the passage of time, and addition of various contaminants, has simply become another form of varnish. You won't remove rust from a gun with a soak type of cleaner that won't also remove case colors or blue. Period.
For either varnish form, nothing works better than old fashioned, dip type carburetor solvent. It is designed to safely remove varnish from aluminum, brass and steel parts, although there is usually a warning on the can NOT to soak aluminum or non-removable phenolic parts overnight. I've used it on cyanide and bone pack case colored parts with no ill effects, ditto on hot and rust blued parts. I've never had to soak gun parts for more than about 20 minutes. 5 or 10 minutes usually is plenty.
The stuff is nasty, and I typically follow the soak with a very hot water rinse, followed by a soak in mineral spirits and a spray with a light lubricant to hold off oxidation until I get back to assembly.
Do not attempt to use dip carb solvent indoors. Use gloves when you are around it. I've found nothing that works better, or faster.
Best,
Ted